Interleukin-1 (IL-1) is a monokine which has been demonstrated to produce a variety of seemingly diverse metabolic events including fever, neutrophilia, anorexia, altered mineral metabolism, muscle catabolism, and fibroblast proliferation. Because many of the clinical features of alcoholic hepatitis are metabolic abnormalities that have been shown to be caused by IL-1, we questioned whether patients with alcoholic hepatitis had elevated serum levels of IL-1. Six patients with alcoholic hepatitis had serum IL-1 activity measured by the thymocyte costimulator assay after serum inhibitors were removed. Their values were compared to those of 6 age and sex-matched healthy controls. Patients with alcoholic hepatitis had markedly elevated serum IL-1 activity, with the integrated value of all fractions having serum IL-1 activity being 9.8 times that of controls. IL-1 activity in serum from alcoholic hepatitis patients also was blocked by antibody to IL-1. We conclude that patients with alcoholic hepatitis have increased serum IL-1 activity which may play a role in certain of the metabolic complications of alcoholic hepatitis.