The etiology of most endocrine disorders remains unknown. Although viruses have been suggested as possible etiologic agents, this area has received relatively little attention. Scattered throughout the literature, however, are a number of case reports which contain clinical and pathological evidence of endocrine involvement during and after certain viral infections. The purpose of this report is to review the clinical and experimental literature, critically examine the relationship between viral infections and endocrine disease, and discuss experimental approaches which might aid in studying the effect of viruses on endocrine function.