1989–90 South Midlands League

The 1989–90 South Midlands League season was 61st in the history of South Midlands League.

Premier Division
The Premier Division featured 17 clubs which competed in the division last season, along with 2 new clubs:
 * Welwyn Garden United, promoted from last season's Division One
 * Milton Keynes/Wolverton Town, relegated from Isthmian League Division Two North

Division One
The Division One featured 11 clubs which competed in the division last season, along with 5 new clubs:
 * Wingate, joined from Herts County League Premier Division
 * Shenley & Loughton
 * Bedford United
 * Toddington Rovers
 * Risborough Rangers