The London–Sydney Marathon was a car rally from the United Kingdom to Australia. It was first run in 1968, a second event by the same organizers was run in 1977 and a third in 1993 to commemorate the 25th anniversary of the original. Three further rallies have subsequently been contested in 2000, 2004 and 2014.

The 1968 event inspired different organizers to create the 1970 London to Mexico World Cup Rally, the 1974 London-Sahara-Munich World Cup Rally, and the Dakar Rally.

The original 1968 event was won by Andrew Cowan, Colin Malkin and Brian Coyle, driving a Hillman Hunter. Fifty-six cars finished.

The success of the 1968 marathon spawned the World Cup rallies, although after the controversial 1974 event, no further World Cup event would be held. While the original event was to prove a triumph for the Rootes Group, the 1977 edition, this time sponsored by Singapore Airlines, was dominated by Mercedes-Benz. The German marque claimed a 1–2 finish and had two other cars in the top eight, with Andrew Cowan in a 280E repeating his success of nine years previous, followed home by teammate Tony Fowkes in a similar car. Paddy Hopkirk, this time driving a Citroën CX, took the final podium spot.^[15][16]

Nick Brittan, a competitor in the original event in a Lotus Cortina, established his company as an organiser of modern endurance rallies with a 25th anniversary re-run of the marathon in 1993.^[17] He persuaded 21 drivers who had competed in 1968 to return, including Andrew Cowan and Roger Clark, and altogether 106 teams from 17 countries entered. Cowan drove the same car as the first time, having his Hillman Hunter loaned to him by the Scottish Automobile Club museum, while other competitors drove pre-1970 era cars. The entry fee was £12,900, and the estimated cost of participating was put at £45,000.^[18]

The 16,000 km rally had three major differences to its ancestor. First, the changing political climate in the Middle East meant that several countries such as Iran and Afghanistan were now out of bounds, although in Europe, Turkey and Australia much of the original route was retraced. Also, the old scheduled open road sections were replaced with more modern timed special stages for safety reasons. Finally, with the demise of the great passenger liners there would be no great voyage across the Indian Ocean to Australia, Brittan instead negotiating for two Antonov An-124 cargo planes to take the vehicles to Australia.^[17]

The winning driver was Francis Tuthill in a Porsche 911, ahead of the Ford Falcon GT of Ian Vaughan who finished third in 1968. Kenya's Mike Kirkland, a stalwart of the Safari Rally, took the final place on the podium in a Peugeot 504.

A second rerun was organised in 2000 as a "Millennium celebration of [the] first epic event."^[19] Again, much of Asia was inaccessible for political reasons, with two airlifts instead of the single one of 1993. Now, after crossing Europe and Turkey in the first fourteen days, the competitors would be loaded on to the Antonovs for the trip to northern Thailand, driving south through the country and into Malaysia for twelve days before being flown to Australia for the last eight days of the rally.

Of the 100 starters who left London 78 reached Sydney, with Stig Blomqvist and Ben Rainsford scoring victory ahead of Michèle Mouton in a Porsche 911, whose co-driver was 1993 winner Francis Tuthill. Rick Bates and Jenny Brittan in another 911 took third.

The third re-run was a combination of modern Group N (showroom-class) cars, and pre-1977 classics, all limited to two wheel drive and a sub-two-litre engine. New Zealand, in tandem with Lincolnshire, England race-preparation specialists Langworth Motorsport, scored a 1–2–3 podium clean sweep with three Kiwi-piloted Honda Integras; overall winners Joe McAndrew and Murray Cole, runners-up Mike Montgomery and Roy Wilson, and Shane Murland and John Benton in third. The highest-placed classic car was a Ford Escort RS1600 driven by Britain's Anthony Ward and Mark Solloway, which finished sixth overall.^[20]

Ten years later a sixth Marathon was run. Differing from its five predecessors it was run in the reverse direction, starting in Sydney and travelling to London with an airlift linking the west coast of Australia to Turkey.