A cross-sectional study and a retrospective study were performed to determine the frequency of balanitis in a randomly selected group of dermatology patients. A total of 398 subjects were included in the cross-sectional study, 213 (53.5%) of whom had been circumcised. Balanitis was diagnosed in 2.3% of circumcised men and in 12.5% of uncircumcised men. In patients with diabetes mellitus, balanitis occurred with a prevalence of 34.8% in the uncircumcised population, compared with 0% in the circumcised population. Balanitis did occur with increased frequency in the diabetic population (16%), regardless of circumcision status, compared with the nondiabetic population (5.8%). Of 63 circumcisions performed at our institution between 1987 and 1989, 28.6% were for the treatment of balanitis; 44.4%, for phimosis (which was probably induced by chronic balanitis); 19% in preparation for placement of penile prostheses; and 8% for miscellaneous reasons. No complications of circumcision were reported. In this group of patients, balanitis was more frequent in diabetic than in nondiabetic uncircumcised men (50% vs 15.4%).