Prophylactic effects of N-benzoyl-beta-alanine (betamipron, BP), one of a series of N-acyl amino acids, were examined against cisplatin-induced nephrotoxicity. Male Wistar rats were injected i.p. with 6 mg/kg of cisplatin combined with an i.p. BP dose given at various times and various doses. Rats were sacrificed 5 days after cisplatin injection to weigh the kidney and liver, and to determine blood urea nitrogen (BUN) and serum creatinine (serum Cr) levels. Preliminary results suggest that treatment with BP is an effective means of protection against cisplatin-induced nephrotoxicity. Combination with BP reduced the weight loss following treatment with cisplatin. The ratios of the kidney and liver weights to the body weight in the animals treated with cisplatin followed later with BP are significantly different (p < 0.05) from those in the animals that received only cisplatin. The BUN and serum Cr levels in the animals treated with cisplatin followed from -1 to 4 hr, and from -4 to 4 hr later with 250 mg/kg BP dose and followed 1 hr later with from 250 to 1000 mg/kg, and from 250 to 2000 mg/kg BP doses differed significantly (p < 0.05) from those in the animals that received only cisplatin. Histological analysis of the kidneys confirmed the protective effect of BP.