The fictional film is shot like a homemade movie
Low budget horror Paranormal Activity has landed at number one in the North American box office chart.
The film, which reportedly only cost $15,000 (£9,200) to make, took $22m (£13.5m) in its first weekend on nationwide release.
It trounced the sixth instalment of the horror franchise Saw, which opened at two with the worst takings in the series' history with $14.8m (£9.1m).
Last week's number one film, Where The Wild Things Are, fell to number three.
Saw's previous low was $18.3m (£11.2m) for the original movie, with its subsequent instalments all opening at $30m (£18.4m) or above.
Thanks to online positive word-of-mouth interest, Paramount Pictures decided to release Paranormal Activity nationwide after playing to sold-out crowds at midnight-only screenings for the past four weekends.
US BOX OFFICE TOP FIVE
1 Paranormal Activity - $22m
2 Saw VI - $14.8m
3 Where The Wild Things Are - $14.4m
4 Law Abiding Citizen - $12.7m
5 Couples Retreat - $11.1m
The fictional movie, shot like a homemade documentary, follows a couple coping with apparitions and supernatural phenomena in their home.
Its success on wider release brings its total box office takings to $62.5m (£38.3m).
Other new releases in the top 10 included animated film Astro Boy at six and Cirque du Freak: The Vampire's Assistant at eight.