Most of the studies included in this review were not designed, or were not sufficiently methodologically sound, to address the sexual preference hypothesis of rape. Therefore, the results obtained are of uncertain generalizability to rapists. There is disagreement in the literature as to the utility of phallometry with rapists. Phallometry is a procedure for assessing sexual arousal in males based on penile tumescence. It is often used in clinical practice with convicted sex offenders to assess potential pretreatment need, treatment effectiveness, and/or recidivism risk. In an attempt to better understand the basis for the disagreement and contradictory conclusions, this article begins with a discussion on the theoretical rationale for assessing sexual interest via phallometry. Second, all the recent (i.e., since 1994) studies that have used phallometric assessment to measure sexual arousal in convicted rapists of self-identified sexual aggressors are individually reviewed and critiqued. The article concludes with a listing of the strengths and weaknesses of the literature with overall conclusions drawn, and recommendations in the need for improvements and directions for future research. References