Peritoneoscopic findings of 39 patients with alcoholic liver cirrhosis (ALC) were compared with those of 95 patients with non-alcoholic liver cirrhosis (NALC). They were selected from 245 patients with liver cirrhosis subjected to peritoneoscopy in the 7 year period from 1975 to 1981. Out of the 95 NALC patients, 24 had hepatitis B surface antigen. The ALC patients had nodules which varied in size (61%), large depressions (69%), and a markedly rounded edge of the liver (33%) more often than NALC patients (18, 43 and 3%, respectively). Nodularity differed between the right and left lobes in ALC (41%) more often than in NALC (16%). Interstitial reddish markings and patchy nodules were, however, more frequent in NALC (51 and 28%, respectively) than in ALC (8 and 5%, respectively). Lymphatic vesicles were observed both in ALC (85%) and NALC (78%). In conclusion, the peritoneoscopic features which suggested ALC were the coexistence of nodules of various sizes, large depressions and a markedly dull edge of the liver. Interstitial reddish markings and patchy nodules were more indicative of NALC than ALC.