The Welsh Rugby Union Division Four South East (also called the SWALEC Division Three South East for sponsorship reasons) is a rugby union league in Wales.

There are 12 clubs in the WRU Division Three South East. During the course of a season (which lasts from September to May) each club plays the others twice, once at their home ground and once at that of their opponents for a total of 22 games for each club, with a total of 132 games in each season. Teams receive four points for a win and two point for a draw, and additional bonus win is awarded to either team if they score four tries or more in a single match. No points are awarded for a loss though the losing team can gain a bonus point for finishing the match within seven points of the winning team. Teams are ranked by total points, then the number of tries scored and then points difference. At the end of each season, the club with the most points is crowned as champion. If points are equal the tries scored then points difference determines the winner. The team who is declared champion at the end of the season is eligible for promotion to the WRU Division Three South East. The two lowest placed teams are relegated to the WRU Division Five South East.