Brain areas activated in human male sexualbehavior have not been characterized precisely. For thefirst time, positron emission tomography (PET) was usedto identify the brain areas activated in healthy males experiencing visually evoked sexualarousal. Eight male subjects underwent six measurementsof regional brain activity following the administrationof [¹⁵O]H₂O as they viewedthree categories of film clips: sexually explicit clips,emotionally neutral control clips, and humorous controlclips inducing positive but nonsexual emotions.Statistical Parametric Mapping was used to identifybrain regions demonstrating an increased activity associatedwith the sexual response to the visual stimulus.Visually evoked sexual arousal was characterized by athreefold pattern of activation: the bilateralactivation of the inferior temporal cortex, a visualassociation area; the activation of the right insula andright inferior frontal cortex, which are two paralimbicareas relating highly processed sensory information with motivational states; and the activation ofthe left anterior cingulate cortex, another paralimbicarea known to control autonomic and neuroendocrinefunctions. Activation of some of these areas was positively correlated with plasma testosteronelevels. Although this study should be consideredpreliminary, it identified brain regions whoseactivation was correlated with visually evoked sexualarousal in males.