The 1991 Australian Football League season was the 95th season of the elite Australian rules football competition.
Hawthorn defeated North Melbourne 14.19 (103) to 7.12 (54). (For an explanation of scoring see Australian rules football).
Due to the addition of the Adelaide Crows, there was an odd number of teams in the league, requiring byes. Each team played 22 games for the season, with two byes: seven teams had a bye in Round 1, and then one team had a bye in each other week.
All teams played 22 games during the home and away season, for a total of 165. An additional 7 games were played during the finals series.
A team based in the state of South Australia, christened the "Adelaide Crows" after the epithet bestowed upon those from South Australia by those living in other Australian states (viz., the "crow eaters") was admitted to the AFL competition in 1991.
Total match attendance for the home-and-away season was 3,810,868 people. Total attendance for the finals series was 381,707 people. Attendance at the Grand Final was 75,230 people. The largest non-finals attendance was 55,735 people for the Collingwood v Melbourne game of Round 6.The Brownlow Medal was awarded to Jim Stynes of Melbourne
The Coleman Medal was awarded to Tony Lockett of St Kilda
The Norm Smith Medal was awarded to Paul Dear of Hawthorn
The Leigh Matthews Trophy was awarded to Jim Stynes of Melbourne
The Wooden Spoon was "awarded" to Brisbane Bears
Brisbane Bears won the reserves premiership. Brisbane 16.13 (109) defeated Melbourne 11.9 (75) in the Grand Final, held as a curtain-raiser to the seniors Grand Final on 28 September at the Melbourne Cricket Ground.
The Adelaide Crows entered the AFL competition.
The McIntyre "Final Five" system, which had operated from 1972 until 1991, was replaced by the First McIntyre "Final Six" system. This system lasted only this season, and it was replaced by the Second McIntyre "Final Six" system in 1992.
In Round 6, North Melbourne and Sydney kicked 32.18 (210) in the first half. It is the only aggregate of 200 points for a half in VFL/AFL history.
In Round 11, Carlton kicked its only goal through Mark Arceri 33 seconds from the end of their match with Footscray. It was the Blues' lowest score since 1904, and the closest a team has come to a goalless match since 1961.
In Round 21, Essendon hosted its last senior VFL/AFL match at Windy Hill—its home venue since 1922. Essendon played its home matches at the Melbourne Cricket Ground for the remainder of the 1990s.
West Coast did not concede more than 100 points in any game during the home-and-away season, being the first team to do this since 1967.
The Qualifying Final at Subiaco Oval between West Coast and Hawthorn was the first finals match played outside Melbourne since 1897, when one finals match was played in Geelong; it was the first final ever played outside Victoria.
The capacity of the Melbourne Cricket Ground was reduced by half during 1991 as the new Great Southern Stand was constructed in preparation for the 1992 Cricket World Cup, to be played there in the summer of 1991/92. One consequence of this was that Waverley Park hosted all finals that were played in Melbourne, including (for the first and only time in its history) the Grand Final. The other was that Hawthorn's plans move its home games from Princes Park to Waverley Park were delayed by one year: Hawthorn had played five home games at Waverley Park and six at Princes Park in 1990 as part of transitional arrangements for a permanent move in 1991, but the AFL reneged on the deal when it became clear that the ground was needed for blockbuster games throughout the year; as a compromise, Hawthorn again played five home games at Waverley Park and six at Princes Park during 1991, and then moved permanently to Waverley Park in 1992.
By the end of the year, Hawthorn captain Michael Tuck retired from the game, having played a record 426 VFL/AFL matches (including 7 premierships from 11 grand finals).