Sexual activity decreased with age comparably in 48 middle-aged, middleclass male subjects with arteriosclerotic heart disease (ASHD) and in 43 who were judged normal coronary-prone. In 58% (28) of subjects with ASHD, it decreased further after the development of a myocardial infarct. Symptoms of coronary insufficiency infrequently influenced return to sexual activity. The cardiovascular cost of conjugal sexual activity with mates of 26 years was relatively low. Sexual activity was influenced favorably by enhancement of physical fitness. Counseling about sexual activity for patients with ASHD must include both physical and psychological factors. A physiological measure to test the adequacy of the advice may be obtained by electrocardiographic electromagnetic tape-recording monitoring of sexual activity in the privacy of the individual's home ("sexercise" tolerance test). This was performed on a subsample of 14 men with ASHD.