The persistent or recurrent inability or lack of desire to perform sexually or engage in sexual activity.

Sexual dysfunction involves both somatic and psychic phenomena which contribute to an overall inability or lack of interest in performing sexually. In males, the condition is most associated with erectile dysfunction (ED), formerly referred to as male "impotence." Studies estimate that 10-20 million American males have some degree of ED, which clinically presents as a persistent inability to attain or maintain penile erection sufficient for sexual intercourse.

Female sexual dysfunction falls into four main categories: (1) a low libido or aversion to sex; (2) difficulty in attaining sexual arousal; (3) inability to experience or attain orgasm; and (4)