A record number of 482,009 students from 2,842 schools entered.
Results are given below for the 1991 AMC, held on Tuesday 30 July. There was 1 perfect score.
Medals were presented at a function held at Parliament House, Canberra, on Friday 14 October, by the Governor-General of Australia, the Honourable Bill Hayden.
| AMC Medallists from the Junior, Intermediate & Senior Divisions |
 |
| Crichton Timothy |
Collegiate School of St Peter SA |
Year 8 |
| Dancer Karen |
Brisbane Girls Grammar School QLD |
Year 7 |
| Deane Gordon |
Launceston Christian School TAS |
Year 8 |
| Dyda Natalie |
Westminster School SA |
Year 8 |
| Hall Tom |
Murray Bridge High School SA |
Year 8 |
| Hanson-Bratton Gideon |
Merewether High School NSW |
Year 8 |
| Ho Jurn |
James Ruse Agricultural High Sc'l NSW |
Year 7 |
| Mailes Oliver |
Christ Church Grammar School WA |
Year 8 |
| Miller Ian |
Launceston Church Grammar School TAS |
Year 8 |
| McGowan James |
Ashburton College NZ |
Year 8 |
| Ong Glen |
Xavier School PHI |
Year 8 |
| Ross Kevin |
Burnside High School NZ |
Year 8 |
| Yao Andrew |
Gosford High School NSW |
Year 7 |
| Zheng Weili |
The Chinese High School SIN |
Year 8 |
|
| Bull Brian |
Burnside High School NZ |
Year 10 |
| Calegari Frank |
Melbourne Grammar School VIC |
Year 10 |
| Hawkins William |
Canberra Grammar School ACT |
Year 9 |
| Henderson Anthony |
Sydney Grammar School NSW |
Year 10 |
| Lau Karen |
Tintern Grammar School VIC |
Year 9 |
| Lin Ziwei |
The Chinese High School SIN |
Year 10 |
| Mitchell Andrew |
Knox Grammar School NSW |
Year 10 |
| Tangaroa Emil |
Burnside High School NZ |
Year 10 |
| Wilkin Graeme |
Scotch College VIC |
Year 10 |
| Yamamoto Hideko |
Ku-ring-gai High School NSW |
Year 10 |
| Young David |
Haileybury College VIC |
Year 10 |
 |
| Backsai Zoltan |
Casuarina Secondary College NT |
Year 12 |
| Brown Mark |
Kingswood College VIC |
Year 12 |
| Burton Benjamin |
John Paul College QLD |
Year 11 |
| Chua Chek-Beng* |
Hwa Chong Junior College SIN |
Year 11 |
| Fung Avery |
Randwick Boys High School NSW |
Year 12 |
| Ip Lawrence |
Melbourne Grammar School VIC |
Year 11 |
| Kameron Luke |
Knox Grammar School NSW |
Year 12 |
| Lau David |
Yarra Valley Anglican School VIC |
Year 12 |
| Richer Duncan |
The Heights School, Modbury Heights SA |
Year 12 |
| Sawon Justin |
Heathfield High School SA |
Year 12 |
| Sellner Stuart |
Rossmoyne Senior High School WA |
Year 12 |
| Tan Meng |
Brisbane Grammar School QLD |
Year 12 |
| * denotes perfect score: BH Neumann certificate |