Despite the fact that a substantial minority of individuals describe sexual thoughts that are perceived as unwanted and unacceptable, for the most part sexuality researchers have not differentiated sexual thoughts and fantasies that are perceived as positive by the respondent from those which are perceived as negative. At the same time, cognitive-behavioral researchers investigating intrusive thoughts-that is, unwanted, sudden, and involuntary ego-dystonic thoughts and obsessions-have not distinguished those reflecting sexual themes from those reflecting other themes. The purpose of this study was to examine sexual intrusive thoughts in a nonclinical population. One hundred seventy-one college students participated in the study and were administered measures assessing intrusive thoughts, psychological distress, and disposition towards sexuality. Sexual intrusive thoughts were reported by 84% of participants. Compared to the women, the men reported a greater number of different sexual intrusive thoughts, and marginally more frequent sexual intrusions. In addition, the men reported more frequent sexual intrusive thoughts involving some active, aggressive themes and less frequent thoughts of being sexually victimized than did the women. Compared to the men, the women reported less sexual arousal in response to their most upsetting intrusive thought. Greater erotophilia, more frequent sexual daydreaming, and more frequent obsessive thoughts uniquely predicted the frequency of sexual intrusions. This indicates that sexual intrusive thoughts are not just a result of general psychopathology or psychological distress, but also have a large sexual component. Two patterns of experiencing sexual intrusions are delineated.