National League 2 South (known before September 2009 as National Division Three South) was a level four league in the English rugby union system until the end of season 2021–22. It was one of two leagues at this level, with its counterpart, National League 2 North, covering the north of England. The format of the league was changed at the beginning of the 2009–10 season following reorganisation by the Rugby Football Union. The champions were promoted to National League 1. The runner-up play in a promotion play-off with the runner-up of National League 2 North; the team with the best record having home advantage. The bottom three teams were relegated, to either South West Premier or London & South East Premier. Esher are the current and final champions.