Pole Day Time trials – Saturday May 18

Graham Hill, the 1966 winner in the #70 STP Turbine, was first to qualify and set a new qualifying record. Later, his STP Lotus 56 teammate Joe Leonard in #60 won the pole position with a four-lap average speed of 171.559 mph (276.1 km/h).

Second Day time trials – Sunday May 19

Rain kept cars off the track most of the day. Only two cars were able to make an attempt, and only one was run to completion. At 5:45 p.m., the track was finally opened for qualifications, and Jochen Rindt was the lone qualifier at 164.144 mph (264.2 km/h), while Denny Hulme waved off as the 6 o'clock gun went off.

At the conclusion of the first weekend of time trials, the field was filled to 16 cars.

Third Day time trials – Saturday May 25

Sixteen cars made a total of 24 attempts, and filled the field to 26 cars. High winds kept some cars off the track, and speeds were down from the previous weekend.^[8] Many cars waved off, and Mel Kenyon, at 165.191 mph (265.8 km/h), was the fastest of the day.

After qualifying, Ronnie Bucknum's car was disqualified for being twenty pounds (9 kg) underweight.

Fourth day time trials – Sunday May 26

With the field filled to 25 cars (eight spots open), rain kept the cars off the track until late in the day. The final scheduled day of time trials ("Bump Day") was almost a complete wash out. The traditional 6 o'clock closing time came and went, and the track was still wet. Track crews continued to work, and the track opened for practice at 6:55 p.m. After the mandatory 30-minute practice session, the track opened for time trials at 7:31 p.m.

With overcast skies and darkness looming, three cars made attempts. Bill Puterbaugh and Bill Cheesbourg completed runs, while Bobby Johns spun on his second warm up lap. At that time, officials deemed the conditions unsafe due to darkness, and postponed the remainder of qualifying until Monday morning.^[9]

Time trials – Monday May 27

For the first time since 1952, time trials were pushed into a fifth day.^[9] Officials ruled that all 25 cars that were in the starting field at 6 p.m. Sunday (May 26) were "locked in" and could not be bumped. In addition, all cars that were in line to qualify Sunday evening at 7:54 p.m. were eligible to make one qualifying attempt on Monday. Only cars that qualified after 6 p.m. on Sunday evening were subject to bumping (including Puterbaugh and Cheesbourg).

Ronnie Bucknum was reinstated to the field when it was determined that during his inspection, the scale used to weight the car was defective.^[10] With Bucknum's car back in the field, only seven spots were now available.

Though rain hampered the day, the qualifying was successfully completed on Monday. A frantic session saw two crashes (Bob Hurt and Rick Muther). Eighteen cars took to the track to fill the seven open spots. Both Puterbaugh and Cheesebourg were bumped, and Mike Mosley was the fastest of the day. Jim Hurtubise qualified his front-engined Mallard for 30th starting position. It would be the final front-engined car to qualify for the Indy 500.

Alternates

• First alternate: Bruce Walkup  R  (#59, #62)^[11]

Failed to qualify

• Sonny Ates  R  (#19, #31)
• Rollie Beale  R  (#32, #88)
• Chuck Booth (#34) – Entered, did not drive
• Bill Cheesbourg (#22, #75, #81)
• Jim Clark – Withdrawn
• George Follmer  R  (#28, #41, #42)
• Masten Gregory (#28, #95)
• Bob Harkey (#71, #77, #88)
• Chuck Hulse (#90) – Wrecked practice, retired
• Bob Hurt  R  (#11, #14, #36, #72, #81, #90)
• Bobby Johns (#17, #25)
• Dee Jones  R  (#34, #46)
• Ralph Ligouri  R  (#71, #77, #88)
• Bruce McLaren  R  (#66, #69)
• Al Miller (#9, #32)
• Rick Muther  R  (#22, #28)
• Danny Ongais  R  (#63) – Entry declined, lack of experience
• Henry Pens  R  (#17) – Entry declined, lack of experience
• Bill Puterbaugh  R  (#63, #71, #77)
• Les Scott  R  (#50) – Failed refresher test
• Mike Spence  R  (#30, #60) – Fatal accident
• Chuck Stevenson (#90) – Wrecked, retired
• Jackie Stewart (#20)
• Jerry Titus  R  (#50, #71, #75, #76)
• Greg Weld  R  (#17, #19, #30)
• Dempsey Wilson (#51, #63, #81)
• LeeRoy Yarbrough (#59, #62)^[12]

First half

At the drop of the green flag, Joe Leonard in the #60 STP Turbine took the lead, with Bobby Unser in second and Roger McCluskey up to third at the end of lap one. A fast pace was set over the first 100 miles, with no yellow caution lights. Bobby Unser took the lead for the first time on lap 8, and led most of the first half.

After only nine laps, Jim Hurtubise in the front-engined PepsiCo Frito-lay special had burned a piston, and was out, finishing 30th, the final front-engined "roadster" to race at lap at the 500. Also in the pits was Mario Andretti, who dropped out with a bad piston. Moments later, he hopped into the car of his teammate Larry Dickson, but that was also short-lived. That car also suffered a broken piston after 24 laps.

On lap 41, the caution flag flew for the first time. Al Unser Sr. made a routine pit stop, but a fire broke out in the turbocharger. He was able to return to the race, but after only one lap, he lost a wheel and hit the wall in turn one. Arnie Knepper and Gary Bettenhausen were also involved. After 200 miles (320 km), defending champion A. J. Foyt was out with a blown engine.

Second half

On lap 110, Graham Hill lost a wheel and smashed into the turn two wall, which brought out the second caution. It was the first of the three Granatelli Turbines to drop out of the race. On the restart, Bobby Unser took the lead, blowing by Joe Leonard, showing the traditional piston-powered engines were still a match for the powerful turbines.

On lap 127, Mel Kenyon and rookie Billy Vukovich II tangled in turn four. Both were able to re-enter the race, but Johnny Rutherford, while trying to slow down, was rear-ended by Jim McElreath. Mike Mosley also spun into the turn four grass trying to avoid the accident. Rutherford was out, but McElreath limped back to the pits where his crew repaired the nosecone.

When Bobby Unser made his last pit stop on lap 166, his gearshift linkage was broken, and the car was stuck in high gear. As he slowly left his pit, struggling to accelerate back to racing speed, both Leonard and Ruby passed him. Leonard now led in the Turbine. Ruby was up to second, but moments later on lap 178, Ruby was back in the pits with a faulty ignition coil. His crew was able to replace the coil, but the six-minute pit stop dropped him out of contention for the win.

With 19 laps to go, Joe Leonard led, with Bobby Unser back up to second. Carl Williams crashed on the backstretch, triggering a fire which brought out the yellow light. Under the caution, Leonard led, with Bobby Unser second, and Dan Gurney in third. For a brief moment, a controversy started brewing as Art Pollard (teammate to Joe Leonard), who was a couple laps down, was not keeping up with the caution pace. As a result, Bobby Unser was stuck behind him, and losing track position to Leonard.

Finish

After the cleanup, the green flag was given to the field at the start of lap 192. At that instant, both leader Joe Leonard and his teammate Art Pollard hesitated and instantly slowed with identical snapped fuel pump drive shafts. The turbine engines again failed in sight of the finish, stunning the racing fraternity. Bobby Unser swept by into the lead with Dan Gurney inheriting second place. With a nearly full-lap lead, Unser cruised over the final nine laps to win his first Indianapolis 500.

Cars using Goodyear tires swept the top four positions, and Goodyear won their second 500 in row. Officials allowed the top five cars to finish the full 500 miles, then flagged the rest of the field off the track. This would be the final 500 in which finishers were named to the prestigious Champion Spark Plug 100 mph Club. Unlike the 1967 race, the Turbine did not run away from the field in 1968. Bobby Unser led the most laps in the Offenhauser, but Joe Leonard spent most of the day on Unser's tail, in the top three. Graham Hill ran in the top five, but complained that he lacked speed down the long straights, and was running 4th when he wrecked. Art Pollard, in the third Turbine, spent most of the day in the top ten before the car quit, but was never really a factor for the win.

Race statistics

Radio

The race was carried live on the IMS Radio Network. Sid Collins served as chief announcer. Len Sutton served as "driver expert" for the third year. At the conclusion of the race, Lou Palmer reported from victory lane.

Pre-race coverage was 30 minutes. The entire on-air crew remained consistent from 1966 & 1967. The broadcast was carried by over 900 affiliates including 761^[13] in the United States, Armed Forces Network, the CBC, and reached New Zealand and Australia for the first time. The broadcast had an estimated 100 million listeners worldwide.

Collins greeted numerous guests in the booth during the race. Among those who stopped by were Chuck Stevenson, Sam Hanks, J. C. Agajanian, former (and future) radio analyst Fred Agabashian, Duke Nalon, Pete DePaolo, Henry Banks, Tom Binford, Johnnie Parsons, and Johnny Boyd. Indiana Senator Vance Hartke visited the booth, escorting a delegation that included Secretary of Transportation Alan Boyd, FCC chairman Rosel H. Hyde, Utah Senator Frank Moss, and Jack Kauffmann (The Washington Star). Senator Birch Bayh also visited the booth, accompanied by his teenage son, future governor and future senator Evan Bayh, who was attending his first race. On the air, Evan correctly predicted Bobby Unser would win the race.

Television

The race was carried in the United States on ABC's Wide World of Sports. The broadcast was supposed to air on Saturday, June 8 but was postponed a week to Saturday June 15 due to the funeral that day of Senator Robert F. Kennedy. Jim McKay anchored the broadcast with Rodger Ward as analyst, and Chris Economaki as a pit reporter..

The race was shown live on MCA closed-circuit television in approximately 175 theaters across the United States.^[14][15] Charlie Brockman served as anchor.