The 1991 AFL season was the 95th season of the Australian Football League (AFL), which was known previously as the Victorian Football League until 1989. The season ran from 22 March until 28 September, and comprised a 22-game home-and-away season followed by a finals series featuring the top six clubs, an increase from the top five clubs which had contested the finals since 1972.
The season saw expansion of the league to fifteen clubs, with the admission of the newly established Adelaide Crows, based in Adelaide, South Australia. With at least one team representing each of the three major Australian rules football states, the league was now the highest level senior Australian rules football competition across Australia, as well as the top administrative body for football in Victoria.
The premiership was won by the Hawthorn Football Club for the ninth time, after it defeated by 53 points in the 1991 AFL Grand Final.
Foster's Cup
defeated 14.19 (103) to 7.12 (54) in the final.
Home-and-away season
The league expanded to 15 teams with the admission of the Adelaide Crows, meaning byes were required for the first time since 1943.
Each team played 22 games for the season with two byes: seven teams had a bye in round 1, and one team had a bye in each subsequent round.
Round 1
Round 2
|- bgcolor="#CCCCFF" | Home team | Home team score | Away team | Away team score | Ground | Crowd | Date |- bgcolor="#FFFFFF" ||| 8.10 (58) |||| 13.7 (85) ||Waverley Park|| 39,266 ||Saturday 30, March |- bgcolor="#FFFFFF" ||| 6.13 (49) |||| 27.18 (180) ||Princes Park|| 11,278 ||Saturday 30, March |- bgcolor="#FFFFFF" ||| 8.10 (58) |||| 15.14 (104) ||Carrara Stadium|| 5,724 ||Saturday 30, March |- bgcolor="#FFFFFF" ||| 12.9 (81) |||| 15.14 (104) ||Football Park|| 43,850 ||Sunday 31, March |- bgcolor="#FFFFFF" ||| 17.7 (109) |||| 16.17 (113) ||MCG|| 31,793 ||Monday 1, April |- bgcolor="#FFFFFF" ||| 18.22 (130) |||| 16.8 (104) ||Kardinia Park|| 26,303 ||Monday 1, April |- bgcolor="#FFFFFF" ||| 25.16 (166) |||| 10.15 (75) ||Princes Park|| 13,815 ||Monday 1, April
Round 3
|- bgcolor="#CCCCFF" | Home team | Home team score | Away team | Away team score | Ground | Crowd | Date |- bgcolor="#FFFFFF" ||| 18.19 (127) |||| 9.16 (70) ||Princes Park|| 16,651 ||Saturday 6, April |- bgcolor="#FFFFFF" ||| 16.21 (117) |||| 8.10 (58) ||Victoria Park|| 24,691 ||Saturday 6, April |- bgcolor="#FFFFFF" ||| 13.16 (94) |||| 25.17 (167) ||MCG|| 24,961 ||Saturday 6, April |- bgcolor="#FFFFFF" ||| 20.16 (136) |||| 11.13 (79) ||Waverley Park|| 25,960 ||Saturday 6, April |- bgcolor="#FFFFFF" ||| 10.8 (68) |||| 15.27 (117) ||Whitten Oval|| 20,875 ||Sunday 7, April |- bgcolor="#FFFFFF" ||| 21.19 (145) |||| 24.10 (154) ||MCG|| 27,266 ||Sunday 7, April |- bgcolor="#FFFFFF" ||| 15.18 (108) |||| 19.18 (132) ||SCG|| 10,649 ||Sunday 7, April
Round 4
Round 5
|- bgcolor="#CCCCFF" | Home team | Home team score | Away team | Away team score | Ground | Crowd | Date |- bgcolor="#FFFFFF" ||| 19.16 (130) |||| 24.17 (161) ||SCG|| 13,140 ||Friday 19, April |- bgcolor="#FFFFFF" ||| 16.19 (115) |||| 14.9 (93) ||Victoria Park|| 20,403 ||Saturday 20, April |- bgcolor="#FFFFFF" ||| 12.17 (89) |||| 16.17 (113) ||Princes Park|| 12,124 ||Saturday 20, April |- bgcolor="#FFFFFF" ||| 17.16 (118) |||| 16.11 (107) ||Waverley Park|| 21,448 ||Saturday 20, April |- bgcolor="#FFFFFF" ||| 28.14 (182) |||| 17.10 (112) ||MCG|| 22,928 ||Saturday 20, April |- bgcolor="#FFFFFF" ||| 13.17 (95) |||| 8.10 (58) ||Kardinia Park|| 27,365 ||Sunday 21, April |- bgcolor="#FFFFFF" ||| 19.16 (130) |||| 9.11 (65) ||Subiaco Oval|| 34,704 ||Sunday 21, April
Round 6
|- bgcolor="#CCCCFF" | Home team | Home team score | Away team | Away team score | Ground | Crowd | Date |- bgcolor="#FFFFFF" ||| 10.17 (77) |||| 17.11 (113) ||Waverley Park|| 55,735 ||Thursday 25, April |- bgcolor="#FFFFFF" ||| 27.26 (188) |||| 21.8 (134) ||MCG|| 15,664 ||Thursday 25, April |- bgcolor="#FFFFFF" ||| 13.16 (94) |||| 7.18 (60) ||Princes Park|| 29,005 ||Saturday 27, April |- bgcolor="#FFFFFF" ||| 13.11 (89) |||| 19.20 (134) ||Waverley Park|| 33,905 ||Saturday 27, April |- bgcolor="#FFFFFF" ||| 12.11 (83) |||| 16.18 (114) ||Carrara Stadium|| 9,253 ||Saturday 27, April |- bgcolor="#FFFFFF" ||| 11.8 (74) |||| 36.15 (231) ||North Hobart Oval|| 13,335 ||Sunday 28, April |- bgcolor="#FFFFFF" ||| 19.14 (128) |||| 14.13 (97) ||Football Park|| 36,695 ||Sunday 28, April