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We analyzed the facial behavior of 100 volunteers who video-recorded their own expressions while experiencing an episode of sexual excitement that concluded in an orgasm, and then posted their video clip on an Internet site. Four distinct observational periods from the video clips were analyzed and coded by FACS (Facial Action Coding System, Ekman and Friesen 1978). We found nine combinations of muscular movements produced by at least 5% of the senders. These combinations were consistent with facial expressions of sexual excitement described by Masters and Johnson (Human sexual response, 1966), and they included the four muscular movements of the core expression of pain (Prkachin, Pain, 51, 297–306, 1992).