Postherpetic neuralgia was studied in a general-practice population (3,600-3,800) for 26 years, 1947-1972. Postherpetic neuralgia followed 46 (14.3 per cent) of the 321 cases of zoster. No neuralgia occurred after zoster in those under 30 years old. The incidence was strongly associated with age, the highest, 34.4 per cent of the zosters, being in people over 80 years old.Women, especially between 50 and 69 years old, suffered more zoster than men, and women with zoster suffered more postherpetic neuralgia.The incidence of neuralgia was not affected by the anatomical location of the zoster. The duration of neuralgia was unrelated to the age of the patient. Cranial neuralgias lasted much longer on average than neuralgia in other sites. Lumbar and sacral neuralgia were short-lived.