Cisplatin is used widely for the treatment of several types of cancer. Cisplatin-induced nephrotoxicity is serious adverse events, previous treatment such as hydration therapy is insufficient to prevent nephrotoxicity. Cisplatin-induced nephrotoxicity is the dose-limiting adverse events and limits clinical application. In the present study, we applied a drug repositioning approach to identify preventive drugs against cisplatin-induced nephrotoxicity. Using public databases related to gene expression profiling, we identified palonosetron, a 5HT₃-receptor antagonist, as a preventive drug for cisplatin-induced nephrotoxicity. Using a database of self-reported adverse events, we revealed that the reporting odds ratio of palonosetron for cisplatin-induced nephrotoxicity was significantly low, whereas no significant signals were not found with other 5HT₃-receptor antagonists. Using electronic medical records at Mie University Hospital, we validated the preventive effect of palonosetron against cisplatin-induced nephrotoxicity in patients who received cisplatin and fluorouracil therapy with palonosetron or ramosetron. The elevations of serum creatinine and blood urea nitrogen induced by the chemotherapy with palonosetron were significantly lower than that those with ramosetron. We were also able to demonstrate that palonosetron but not other 5HT₃-receptor antagonists ameliorated the survival rate of zebrafish exposed to cisplatin. These findings suggest that palonosetron can reduce cisplatin-induced nephrotoxicity.