Male albino rats were given bleomycin subcutaneously (5 mg potency/kg body weight twice a week) for a period of 6 weeks. At this dosage, mortality was found to be nil with marked fibrotic changes. Pulmonary and cutaneous changes at the end of 2, 4, and 6 weeks of treatment were investigated both by light microscopy and analyses of the intra- and extracellular components. Histologically, fibrosis set in as early as 2 weeks of treatment with bleomycin and was pronounced with increasing duration of treatment. Biochemically, total collagen and hexosamine contents of lung and skin increased significantly compared to control toward the end of treatment period. Thus, this animal model can be conveniently used to mimic the human condition and to test effective antifibrotic agents.