Cystone, a polyherbal ayurvedic preparation, was found to protect rats partially but significantly against cisplatin-induced renal toxicity, when given intraperitonially 1 h before cisplatin. At 500 and 1000 μg/ml, it also inhibited lipid peroxidation induced by cisplatin in renal cortical slices by 62.7 and 71.6%, respectively. The rats pretreated with cystone (1000 mg/kg i.p.) had significantly lower blood urea nitrogen (BUN) and serum creatinine (33.8 and 0.92 mg/dl, respectively) compared to cisplatin alone (51.5 and 1.41 mg/dl, respectively). The control animals had 17.1 and 0.63 mg/dl, respectively. The cystone treated animals lost 5.63 g body weight compared to 12.5 g for cisplatin alone treated animals on day 5. Renal functions like urine to serum creatinine ratio and creatinine clearance showed significant improvement when cystone was given 1 h before cisplatin. However, cystone did not protect increased excretion of urinary protein and decreased WBC count caused by cisplatin. The present study suggests that the cystone protects kidney against cisplatin-induced toxicity and the protection may be mediated through its ability to inhibit lipid peroxidation.