To prevent and to cure liver cirrhosis, we examined the effect of the ethanol extract of berries of Japanese ampelopsis on the collagen formation of rat liver cells in tissue culture. These cells had been transformed to produce collagen fibers very actively. When added at a time of subcultivation, the extract prevented the formation of collagen fibers. When it was added after the formation of collagen fibers, the fibers were fragmented into fine microfilaments.