The US comedy film, which reunites Seann William Scott, Mena Suvari and Jason Biggs nine years after their last instalment of the movie series, made almost $5 million in ticket sales over the weekend.
> 'American Reunion's Shannon Elizabeth: 'We're still all the same'
The sci-fi action movie The Hunger Games, starring Jennifer Lawrence as heroine Katniss Everdeen, drops down to second spot after two weeks in first place.
In third place is comedy The Best Exotic Marigold Hotel, which took $2,146,952, followed by Dr Seuss' The Lorax with $1,856,603.
Other films in the top ten include the 3D re-release of Kate Winslet and Leonardo DiCaprio's Titanic, comedy 21 Jump Street and Julia Roberts's Snow White thriller Mirror Mirror.
The Australian box office top ten in full below (figures in Australian dollars):
1. (-) American Pie: Reunion - $4,801,823
2. (1) The Hunger Games - $3,208,950
3. (2) The Best Exotic Marigold Hotel - $2,146,952
4. (3) Dr Seuss' The Lorax - $1,856,603
5. (-) Titanic 3D - $1,727,962
6. (4) Wrath of the Titans - $1,121,710
7. (5) 21 Jump Street - $1,030,574
8. (6) Mirror Mirror - $881,603
9. (8) Pirates! Band of Misfits - $864,193
10. (10) Salmon Fishing in the Yemen - $567,658
Watch Seann William Scott talk about the American Pie: Reunion experience below: