The relative importance of malnutrition and alcohol toxicity in the pathogenesis of cirrhosis has been controversial. In epidemiological studies the incidence of cirrhosis can be correlated with the duration and amount of alcohol imbibed. The importance of nutrition has been discounted. In these studies few analyses of dietary intake were included. Diets of patients with alcoholic cirrhosis characteristically are poor. Furthermore, alcohol toxicity impairs nutrition by interfering with absorption, transport, and utilization of essential nutrients. Patients with cirrhosis respond favorably to nutritious diets despite the concurrent intake of alcohol, although in lesser amount than their usual intakes. In long-term studies highly nutritious diets have protected rats against cirrhosis from alcohol. However, in acute experiments with "loading" doses there was evidence of direct hepatotoxicity in animals and man. Recently, cirrhosis has been produced in baboons with alcohol and a diet considered adequate. The findings are important, but there is some question whether dietary factors (imbalance) may have played a role. Also of recent interest has been the occurrence of lesions simulating alcoholic hepatitis and cirrhosis after jejunoileal bypass surgery. The evidence suggests that malnutrition may have been a major factor in this disease. The roles of alcohol toxicity and of malnutrition in the pathogenesis of cirrhosis are not fully understood. Further studies are needed to clarify these relationships.