The prevalence of palpable gynecomastia was determined in 306 normal adult men ranging in age from 17-58 yr. Palpable breast tissue was present in 36% and was bilateral in all but 7 subjects. In the great majority of cases, the gynecomastia was 4 cm or less in diameter. A diameter greater than 5 cm was distinctly unusual. With advancing age there was a progressive increase in the prevalence of gynecomastia. This increase was most striking in those over the age of 44 and in the 20- to 24-yr-old group compared to those 19 yr old or less. In those over the age of 44, the prevalence was 57%. These data indicate that palpable gynecomastic is common in normal adult men. This high prevalence must be taken into consideration when attributing gynecomastia to a drug or disease state.