Medical records were reviewed for all 173 cases of herpes zoster diagnosed among residents of Rochester, Minnesota, less than 20 years of age during the period 1960 through 1981. The incidence of zoster increased with age from 20 cases per 100,000 person-years in those residents less than five years of age to 63 cases per 100,000 person-years in those aged 15 to 19. Morbidity was less than has been described in adults, as only two patients required hospitalization and no postherpetic neuralgia or other late complications were diagnosed. The single case of subsequent cancer found in 1,288 person-years of follow-up was not significantly different from the number expected based on cancer incidence in the general Rochester population. The incidence of childhood zoster in patients with acute lymphocytic leukemia was 122 times higher than in children without an underlying malignancy. Chickenpox in the first year of life was found to be a risk factor for childhood zoster, with a relative risk between 2.8 and 20.9. Neither chickenpox in the second year of life nor recent vaccinations were found to be risk factors for childhood zoster.