We conducted an online behavioral survey to estimate the prevalence of online sex-seeking and substance use behaviors and to compare risky behaviors among men using different venues to seek sex with men. A cross-sectional online survey, the Asia Internet MSM Sex Survey, was conducted online from January 1 to February 28, 2010. Of the 1,645 participants enrolled from Taiwan, 72.4% reported the Internet as the main way of seeking sexual partners, 73.9% had had sex with partners found online, and 16% had used recreational drugs in the previous 6 months. There was no evidence to suggest that men who looked for sex through the Internet were more likely to engage in unprotected anal intercourse with their casual partners than those using other gay venues. Having had online sex partners in the previous 6 months was significantly associated with being young [adjusted odd ratio (AOR) = 0.97, 95% CI: 0.95-0.99], having had no steady partners in the previous year (AOR = 0.24, 95% CI: 0.15-0.39), having had more than five partners in the previous 6 months (AOR = 4.57, 95% CI: 2.95-7.11), having used recreational drugs in the previous 6 months (AOR = 2.24, 95% CI: 1.30-3.87), and having had an STI in the previous 6 months (AOR = 4.24, 95% CI: 1.59-11.30). In conclusion, because the Internet is a popular meeting place for MSM in Taiwan, effective and targeted prevention programs should be developed to minimize the HIV transmission risk in the Internet era.