Two plaintiffs claim the site scans private correspondence between users for links to third-party websites, sharing that information with the likes of "advertisers, marketers and other data aggregators."
The suit accuses Facebook of violating the Electronic Communications Privacy Act and California privacy laws.
Facebook has "systematically violated consumers' privacy by reading its users' personal, private Facebook messages without their consent," said the complaint, filed December 30 in the US District Court for Northern California.
"Representing to users that the content of Facebook messages is 'private' creates an especially profitable opportunity for Facebook, because users who believe they are communicating on a service free from surveillance are likely to reveal facts about themselves that they would not reveal had they known the content was being monitored," it said.
The suit was brought forth by two Facebook users from different US states, Matthew Campbell of Arkansas and Michael Hurley of Oregon.
It was filed on behalf of all US Facebook members who have used the site to send or receive a message that includes a link.
"Facebook scanned plaintiffs' messages and searched the website identified in the URL for purposes including but not limited to data mining and user profiling," the suit said.
According to the suit, Facebook earned USD 2.7 billion from targeted advertising sales in 2011.
The suit also said that while Facebook hides the extent of its data mining from users, it is clear on the subject in its technical guidance for web developers.
The case is similar to a lawsuit against Google, which is accused of violating user privacy by scanning the contents of Gmail messages.
Facebook has faced a slew of complaints and court actions on privacy, and last year settled a class action suit over the use of user names and images in so-called "sponsored stories."
A study by the Pew Research Centre released earlier this week revealed that Facebook is the preferred social network in America, used by 71 per cent of online adults, or 57 per cent of all American adults.