1991 New Zealand National Soccer League

The 1991 New Zealand National Soccer League was the 22nd season of a nationwide round-robin club competition in New Zealand football.

Promotion and relegation
Waterside Karori were relegated at the end of the 1990 season, to be replaced by the winner of a play-off series between teams from the northern, central, and southern leagues (Mount Albert-Ponsonby, Nelson United, and Burndale United respectively). Nelson United won the series to gain promotion, but there is some controversy about their participation in the play-offs as they had only finished second in the central regional league, which was won by Petone.

Gisborne City were relegated at the end of the 1991 season.