Background: The Internet has become an important venue for seeking sexual partners and may facilitate transmission of sexually transmitted infections. Methods: We examined a 64-day data log of flirt messages expressing sexual interest among MSM within the Qruiser. com community. We used logistic regression to analyze characteristics of MSM sending and receiving flirt messages and negative binomial regression to examine individual activity and popularity. The structural properties, including the core structure of the flirt network, were analyzed. Results: The MSM population consisted of approximately 40% homosexuals and 37% bisexuals, while the remaining 23% included men who identified as heterosexual but searched for sex with men and experimental. MSM were more likely to send flirt messages if they were homosexual and aged 40+ years; young people aged, 30 years were more likely to receive a flirt. Possession of a webcam was strongly associated with both sending flirt messages and being a flirt target. The distributions of flirts sent (max k(out) = 2162) and received (max k(in) = 84) were highly heterogeneous. Members in central cores were more likely homosexuals, singles, and aged 31-40 years. The probability of a matched flirt (flirt returned from target) increased from 1% in the outer core to 18% in the central core (core size = 4). Discussion: The flirt network showed high degree heterogeneity similar to the structural properties of real sexual contact networks with a single central core. Further studies are needed to explore use of webcam for Internet dating.