The demographic characteristics, behavior, motivations, and psychopathology of same-gender stalkers were compared with a sample of 134 opposite-gender stalkers. The case material was drawn from referrals over a 5-year period (1993-98) to a community forensic psychiatry clinic with a known interest in stalkers and stalking victims. Stalking was defined as repeated (at least 10 times) and persistent (duration of at least 4 weeks) unwelcome attempts to approach and/or communicate with the victim. Where possible, the case material was supplemented with collaborative information in the form of victim and witness statements, police summaries, official criminal records, psychological and psychiatric court reports, psychiatric histories, and media reports. The psychiatric classification for the purposes of this study used DSM-IV criteria. A small subgroup of same-gender stalkers was identified, and their demographic characteristics were summarized by using descriptive statistics. Group differences were analyzed with independent t tests for continuous variables and chi-square or Fisher exact tests, as appropriate, for proportions. Despite the relative frequency of males who reported victimization by male stalkers in large community studies, same-gender stalkers in the current study were more likely to be female. The prior relationship between stalker and victim was less often an intimate one and was more likely to have originated in the workplace. Same-gender stalkers were less inclined to harass their victims by following and unwanted approaches, which may be a reflection of the greater accessibility of their victims within the work setting. Same-gender stalkers were more commonly motivated by resentment than their opposite-gender counterparts. The absence of sexual predators among the same-gender group was consistent with the finding that no paraphilias were diagnosed in these subjects. There was no support in this study for a greater propensity for violence or threats in same-gender stalking. The impact of same-gender stalking on its victims is examined, and the implications of these findings are discussed. 1 table and 25 references