A high rate of personality disorders (PDs) was found in individuals with Internet addiction (IA) in previous studies using clinical and limited sample sizes. The present study further made comparisons between sex and incorporated a control group to compare the frequencies of PD between individuals with IA and those without IA. Five hundred fifty-six college students (341 females) completed self-report surveys and were later given diagnostic interviews to assess for a PD diagnosis. Males with IA showed a higher frequency of narcissistic PD, whereas females with IA showed a higher frequency of borderline, narcissistic, avoidant, or dependent PD when compared with those without IA. The high rate of PD among Internet addicts may be associated with the core features of specific PD psychopathology. Sex differences in the PD frequencies among IA individuals provide indications for understanding the psychopathological characteristics of PDs in Internet addicts.