In February last year, 47 percent of the total online population was made up of women. By December, that percentage had risen to 50 percent, Nielsen/NetRatings said.
Although the gender breakdown regarding overall population has apparently evened, the study showed a dividing line in online behavior between the sexes. Men tend to visit news and information sites, while women are more interested in sites about health and lifestyle, the study said.
This could be a sign of the Internet growing up, according to Alan Weiner, vice president of analytical services for NetRatings.
"We're seeing a smoothing out of gender differences while at the same time seeing the differentiation into how people are using the medium," Weiner said in an interview.
He added that the differences between what women and men prefer online show similarities to the early days of cable television. Men and women have gravitated toward niche cable stations, such as ESPN and Lifetime.
"For a long time (the Internet) was stuck in (the pattern of) white, male, 35, upper income," Weiner said. But as men and women click to sites such as SportsLine and iVillage, the Internet is becoming more of a medium for the masses, he said.
Meanwhile, the total number of U.S. households online jumped last year, from 97 million to 119 million, a 22.7 percent increase over the same period the year before.
The study also showed that users spent eight hours and 17 minutes per month on the Internet, an increase of 10.9 percent. The number of unique sites visited per month decreased 40 percent from 15 sites to nine sites, and the number of page views per session jumped 68 percent from 19 to 32.