From animal research, there is ample evidence for a facilitating effect of dopamine on sexual behavior. In humans, little experimental research has been conducted on the inter-relation between dopamine and sexual response, even less so in women than in men. We investigated the effect of levodopa (100 mg) on sexual response in men and women following a double-blind, placebo-controlled crossover design. Genital and subjective sexual responses were measured as well as somatic motor system activity by means of Achilles tendon (T) reflex modulation. Genital and subjective sexual arousal were not affected by levodopa. However, the drug increased T reflex magnitude in response to sexual stimulation in men, but not in women. These results support the view that dopamine is involved in the energetic aspects of appetitive sexual behavior in men. The observed gender difference in the effect of levodopa is discussed in the perspective of possible dopamine-steroid interaction.