In the country city of Ansbach, Germany all cases of varicellazoster virus infection seen by dermatologists, pediatricians and general practitioners were registered over a period of 16 months, from February 1992 until May 1993. 152 patients were clinically diagnosed with herpes zoster and 437 patients with chickenpox. The population-based incidence of zoster infections was 22.6 per 10,000 inhabitants per year, while the incidence of chickenpox was 42.4. There was a slight predominance of male patients with zoster. There was also a marked influence of age and sex, on the localization of the involved nerve segments. Zoster was seen in patients of all ages but there was a clear predominance in older patients. The peak of the disease occurred in the eighth decade. In patients with chickenpox, the sex ratio was equal. The disease typically occurs in children and we observed a predominance of the cases in the first decade. Spread over the year, zoster was seen equally during all seasons. Chickenpox, however, showed epidemiological peaks of frequency. It is possible that the epidemic spread of the disease and the end of the peak are influenced by special metereological conditions.