In telephone interviews with 1,008 adults, Gallup Poll News Service found that more than half of those polled worried about online privacy.
Particularly troublesome for 60 percent of the respondents were large online databases such as telephone directories, legal documents and property tax information.
About 40 percent said they were also concerned about corporate Web sites gathering marketing information by tracking a consumer's every online move. Additionally, 63 percent were bothered about software that allows the government to tap into personal emails.
The study came as no surprise to privacy advocates, who for the past several years have been rallying for legislation to protect consumers online.
"Everybody in Washington takes it as a foregone conclusion that something needs to be done," said Jason Catlett, founder of Junkbusters, a nonprofit organization based in New Jersey. "Now it's not a question of whether bills are going to be passed but a matter of which one."
Privacy issues peaked earlier this year after consumers became more aware of the information collected about them as they surfed online.
In March, public outcry forced DoubleClick to hold off plans to combine information it collects from consumers online and off.
"The DoubleClick fiasco brought it to the attention of many" that companies were creating dossiers of their consumers, Catlett said. The fear is that the information will end up in the wrong hands, he added.
Gallup's study, conducted Sept. 11 through Sept. 13, has a sampling error of about 3 percentage points.