To study the effects of chronic ethanol feeding with dietary protein deficiency on hepatic fibrosis, the hepatic contents of triglyceride and collagen, and lysyl oxidase activity in the liver were measured in rats fed ethanol with or without a low protein diet for 7 weeks. In the standard-ethanol diet group, hepatic triglyceride content was increased as compared with that in the standard diet group, but hepatic collagen content was not altered. In the low protein-ethanol diet group, hepatic contents of triglyceride and collagen, especially of insoluble collagen, were increased as compared with those of the low protein diet group. Under these experimental conditions, hepatic lysyl oxidase activity was higher in the low protein-ethanol group as compared with those in other three groups, and was correlated significantly with hepatic collagen content. These data suggest that ethanol feeding with a low protein diet resulted in an increased deposition of collagen in the liver, and that hepatic lysyl oxidase activity is one of the factors responsible for collagen deposition.