Simultaneous recordings of the heart rate on the human female and male before, during and after coitus showed a marked increase in heart rate accompanying the orgasm. The response of the male was more uniform than that of the female. A striking parallelism between the response of the male and the female in a given test was observed in several of the experiments. The simultaneous determinations of the pulmonary ventilation showed a marked increase in the rate and minute volume in many of the tests which suggested that hyperventilation occurred during the erotic arousal and especially during the orgasm. Submitted on November 25, 1955