AbstractThe effect of chronic ethanol feeding was determined on parameters of hepatic collagen metabolism in the monkey. Four monkeys of the speciesMacaca radiatareceived a nutritionally adequate diet containing 50% of the calories as ethanol, while four others were pair‐fed a diet in which ethanol was isocalorically substituted by carbohydrate. Liver biopsies were obtained at 3, 12, and 24 months, and the animals were killed between 40 and 48 months after initiation of the diets. The ethanol‐fed animals developed various degrees of fatty infiltration, but no necrosis, inflammation, or fibrosis. The amount and distribution of collagen Types I, III, and IV demonstrated by immuno‐histochemical techniques was not altered after ethanol feeding. No changes were found in hepatic protein‐bound hydroxyproline or in collagen prolyl hydroxylase activity at the various time intervals. Liver free proline and the incorporation of labeled proline into protein‐bound hydroxyproline by liver slices were not altered after 40 to 48 months of ethanol feeding. This study shows that prolonged feeding of ethanol together with an adequate diet results in fatty infiltration but not deposition or alteration of hepatic collagen m