The protective effects of elastase (Ela) and fosfomycin against renal toxicity of cis-diamminedi-chloroplatinum (II) (CDDP) were evaluated in an experimental study using rats. When Ela was used concomitantly with CDDP, the elevation of urinary N-acetyl-β-D-glucosaminidase levels in the early phase and the sharp fall in these levels in the latter phase were prevented. It was also found that the blood urea nitrogen levels and serum creatinine levels were significantly lowered. Histologically, atrophic and necrotic changes in the tubular epithelium were prevented. The total serum platinum levels showed no change with the addition of Ela; however, the platinum levels in the renal tissues were significantly reduced. These results suggested that Ela is effective against platinum deposits in the renal tissues, particularly in the tubular epithelium, thus protecting the kidneys. On the other hand, fosfomycin demonstrated no such positive results suggestive of a protective effect on the renal function parameters or during histological observation.