Intravenous injection of gadolinium chloride (GdCl3) at a dose of 10 mg/kg caused an increase in proliferating cell nuclear antigen labeling index and the grade of pyronin positivity (RNA level) in rat liver. In CCl4-exposed rats, pretreatment with GdCl3 also showed a preventive effect of the liver injury both biochemically and histologically. Moreover, the proliferative action preceded the attenuative effect of the liver injury. Results suggest that GdCl3 induces hepatocyte proliferation, and this action of GdCl3 may modify the development of CCl4-induced liver injury.