Autoradiographic technique was utilized to measure UV-induced DNA repair synthesis in 8 patients with epidermodysplasia verruciformis: 2 infected with human papillomavirus 3 (HPV 3), 4 with HPV 4, and 2 simultaneously with HPV 3 and HPV 4. Two cell populations were compared, i.e. epidermal cells derived from light-exposed and covered skin, and peripheral lymphocytes. A control group consisted of 10 healthy subjects. DNA repair was found to be normal both in the peripheral lymphocytes and in the epidermal cells from exposed and unexposed skin. The values for covered skin were even somewhat higher but this was not statistically significant. The type of HPV infection and malignant conversion had no apparent effect on DNA repair. A certain reduction of the UV-DNA repair synthesis was demonstrated in 2 patients infected with both types of viruses.