A special drug use-results survey was conducted in patients aged 18 years and younger to assess the occurrence of adverse drug reactions, and the safety and efficacy of palonosetron hydrochloride(Aloxi I. V. Injection 0.75 mg/Aloxi I. V. Infusion Bag 0.75 mg)in multiple-course administration in Japan. Between August 2021 and June 2023, 127 patients were enrolled, and all patients were evaluable for safety and efficacy of palonosetron hydrochloride. No adverse drug reactions related to palonosetron hydrochloride were observed. Complete response(CR)rate was 80.3%(102/127 pts)during the acute phase(0-24 hr), 78.0%(99/127 pts)during the delayed phase(24-120 hr), and 70.1%(89/127 pts)during the overall phase(0-120 hr)in Course 1. No decrease in CR rate was also observed even after multiple-course administration. Based on these results, the safety and efficacy of palonosetron hydrochloride in practice do not appear to be any major issues.