This study was performed to investigate the effects of cadmium chloride on the acute and chronic toxicity on rats. Several toxic effects of cadmium has been shown following short-term and longterm pretreatment with cadmium and zinc. Four groups of rats (A, B, C, D), each consisting of 16 rats, were studied and each group was divided into four subgroups (1, 2, 3, 4), 4 rats for each subgroup. Rats were subcutaneously pretreated with $CdCl_2$ (0.5 mg/kg, A & C), and $ZnCl_2$ (13.0 mg/kg, B & D) during time periods of 1 weeks (group A & B) and 6 weeks (group C & D). At the end of the period, rats were challenged with $CdCl_2$ (3.0, 6.0 and 9.0 mg/kg, i.p.). After giving the challenge dose, cadmium and metallothionein(MT) concentrations were determined. The concentrations of cadmium were higher in the liver than the kidney irrelevantly to cadmium and zinc pretreatment and increased dose-dependently to the challenge dosage. The metallothioneins showed higher concentrations in the liver than the kidney following cadmium pretreatment and were higher in the long-term pretreatment groups than the short-term pretreatment groups in the liver and the kidney of rats. These data suggest that metallothioneins are induced preferentially in the liver by pretreatment of cadmium and then, formed in the form of Cd-MT, may play an important role in the nephrotoxicity.