An online poll indicates 60% of people are considering leaving Facebook due to privacy concerns.
The poll, run by internet security company Sophos, also found 16% of those polled had already stopped using the social network due to concerns about inadequate control over their personal information.
These results follow growing criticism of Facebook over changes to the way the social network can share user data across its site and with other websites.
Concerns have centred on the complexity and 'opt-out' approach to sharing member information with wider networks.
Media reports suggest that Facebook is planning to announce changes to its privacy settings shortly, but it is unclear whether any changes will be substantial enough to address user concerns.
"With this survey showing that only 24% of users aren't thinking about quitting, Facebook will need to make sure further changes to the privacy policy are clear, concise and in the interest of making it easier for members to know exactly who has access to whatever they chose to upload", a statement from Sophos said.
The company acknoweledged that people voting in the poll were more likely to have an active interest in security and privacy issues than average internet users.
"But such people are also likely to have the ear of other users, and as privacy and online safety become more key concerns for the public they will look to experts as to whether certain social networks are acting in their best interests or not," the statement said.
"A mass exodus from Facebook seems unlikely, but Facebook members are clearly getting more interested in knowing precisely who can view their data.
"We've seen "delete Facebook account" becoming a hot search term on Google Trends and a number of campaigns, including a 'Quit Facebook Day', spring up to raise awareness of the issues."
Sophos said the poll showed the majority of the people we polled were fed up with the lack of control that Facebook gives them over their own data, and most did not know how to set their Facebook privacy options safely, finding the whole system confusing.
Facebook needed to make a fundamental shift towards asking users to 'opt-in' to sharing information, rather than to 'opt-out', the company said.
However, the poll results do not match statistics reported by Forbes.com: apparently Facebook has had a net gain of 10 million active users since changes to its privacy settings were announced.
In total 1860 people responded to the Sophos poll. The company removed from the results the 272 respondents who said they were not members of Facebook, but kept the separate 254 who said they had already left because of privacy worries.
