1999–2000 Spartan South Midlands Football League

The 1999–2000 Spartan South Midlands Football League season is the 3rd in the history of Spartan South Midlands Football League a football competition in England.

Premier Division
The Premier Division featured 18 clubs which competed in the division last season, along with three new clubs, promoted from the Senior Division:
 * Biggleswade Town
 * Hanwell Town
 * Holmer Green

Senior Division
The Senior Division featured 17 clubs which competed in the division last season, along with three new clubs:
 * Ampthill Town, promoted from Division One
 * Bridger Packaging, promoted from Division One
 * Brimsdown Rovers, relegated from the Premier Division

Also, Milton Keynes changed name to Bletchley Town.

Division One
The Division One featured 14 clubs which competed in the division last season, along with three new clubs:
 * Buckingham Athletic, demoted from the Premier Division
 * Crawley Green, new club
 * Winslow United, relegated from the Senior Division