After 4 weeks of ethanol feeding, collagen synthesis and its degradation system in the liver were investigated in male rats. The ethanol-fed rats had an increased hepatic protein content and a depleted hepatic reduced glutathione content. The content of hepatic hydroxyproline was not changed, however, the synthesis of protein-bound hydroxyproline was significantly increased, the latter was significantly correlated with hepatic protein content and inversely with hepatic reduced glutathione content. The synthesis of protein-bound proline was also increased and significantly correlated with hepatic protein content. Although hepatic collagenase activity was not change, hepatic collagenolytic cathepsin activity was significantly increased, and the latter had a significant relationship to the synthesis of protein-bound hydroxyproline. These results suggest that in the early stage of ethanol feeding, hepatic collagen synthesis is augmented in parallel with general protein synthesis and the newly-synthesized collagen is efficiently removed by collagen degrading system, at least, partly by collagenolytic cathepsins.