Sexual arousal in the male involves a complex interaction of physiological and subjective processes. In recent years, a number of physiological and self-report methods have been described for assessing sexual function in healthy and dysfunctional males. Physiological methods include the Rigiscan, volumetric and circumferential plethysmography, and the erectiometer. Despite their widespread use, each of these approaches has significant limitations in assessing male sexual function. Recent self-report measures include the International Index of Erectile Function (IIEF), Brief Male Sexual Function Inventory (BMSFI), and Center for Marital and Sexual Health Questionnaire (CMSH-SFQ). A structured interview for sexual function assessment has also been described (Derogatis Interview for Sexual Functioning--DISF-SR), in addition to daily diary and event log methods. The relative strengths and weaknesses of each of these approaches are reviewed.