There are reports of decreases in both sexual activity and serum testosterone in older men but not of any clear association between the two variables. In healthy participants in the Baltimore Longitudinal Study on Aging, despite the fact that serum testosterone did not decline with age, sexual activity decreased in a highly predictable fashion. In men over 60 years old, those with higher levels of sexual activity (for age) had significantly greater levels of serum testosterone. Although we found an inverse correlation between testosterone and percentage of body fat, there was no relationship between percentage of body fat and sexual activity. We also found no correlation between testosterone or sexual activity and smoking or coronary heart disease. Subjects drinking more than 4 oz. of ethanol per day were more likely to have decreased sexual activity but not diminished testosterone concentration. Our data suggest that, although serum testosterone level and ethanol intake may affect sexual activity in older men to some degree, age itself still appears to be the most influential variable.