Most of the individuals determined to be sexually compulsive and who used the Internet for sexual activities were men; were likely to be either married, in a committed relationship, or dating; were likely to be bisexual (no homosexuals were found in the compulsive group); and spent either 3-10 hours per week online or more than 15 hours per week online for sexual purposes. Sexually compulsive respondents who spent more than 15 hours online preferred interactive and partner-seeking activities to a greater extent than those who spent less time online. This suggests that the amount of time spent online for sexual purposes may indicate the kinds of sexual activities pursued online rather than the strength of online sexual compulsivity. Those who showed a greater interest in partner-seeking in online sexual activities were more likely to report a sexually transmitted infection. Changes in offline sexual activities in the course of spending time in online sexual activities varied among respondents. Some respondents had abandoned or decreased their offline pornography consumption, but others maintained or even increased their use of offline pornography. Data were collected in 2002 through an online questionnaire in Swedish. Approximately 6 percent of the 1,458 respondents who completed the 10-item sexual compulsivity scale were defined as sexually compulsive. A multivariate regression analysis was used to identify the characteristics of sexually compulsive individuals who engaged in online sexual activities. Bivariate analysis was used to identify any changes in offline sexual behaviors. 2 tables and 25 references