The Celluloid Ceiling study analysed the amount of females working for the top 250 grossing movies in the US. The latest report shows that women made up only 5% of directors during 2011.
The results show a 2% decrease from 2010, and that the amount of women directors has almost halved since 1998. It also revealed that women accounted for only 14% of writers, 18% of executive producers, 25% of producers and 4% of cinematographers.
Chief Executive of Women in Film & TV (UK) Kate Kinninmont said of the findings: "It's shocking to find that gender equality in Hollywood is now actually running backwards.
"When Kathryn Bigelow became the first woman to win the 'Best Director' Oscar in 2010, we hoped this was a sign that the dominant male culture in Hollywood was beginning to drag itself into the 21st century.
"These statistics are appalling, but understanding how bad they are is the first step to making things better. WFTV invites academics working on gender issues in film and television in the UK to contact us. We can publicise their work widely within the industry."
The research was conducted by Dr Martha Lauzen of The Centre for the Study of Women in Television and Film, who explained: "While Bigelow's win was very well-deserved and most likely gave her career a boost, it seems unlikely that issues as complex as bias in women's employment and representation can be so easily resolved."
Kathryn Bigelow is currently working on a movie project about the death of Osama Bin Laden.