We conducted a qualitative analysis of all messages posted in April 2005 on an online discussion forum aimed at recent ex-smokers, on the smoking cessation Web site Stop-tabac.ch. We analyzed only the forum aimed at recent ex-smokers because it was far more active than forums aimed at current smokers. Participants were 97 people who posted a total of 1,033 messages (mean=10.6 messages per participant). Most (76%) participants were women, the median age was 40 years, and participants had quit smoking for a median of 2 months. Each initial message generated on average 2.7 replies. The most frequent categories of messages covered providing emotional support and encouragements (24% of all messages), stories and opinions (14%), congratulations to other quitters (14%), commonplace remarks (13%), “thank you” messages (11%), giving practical advice and tips (8%), and nicotine replacement therapy (6%). Women were more likely than men to post messages on nicotine replacement therapy, congratulations and emotional support. Men were more likely to post general commentaries and practical advice. No individual participant or group of participants had a clear leadership role. The 10 most active participants posted half (49.8%) of all messages. Of these 10 participants, six were still among the 10 most active in May and 3 in June 2005. Thus, this online discussion forum was used mainly by women as a source of emotional support and encouragement during the first few weeks after a quit attempt. The forum was used less frequently as a source of practical information and quitting tips.