Background. A combination of serotonin receptor (5-hydroxytryptamine receptor type 3) antagonists, NK-1 receptor antagonist, and steroid improves the complete response (CR) of chemotherapy-induced nausea and vomiting (CINV) in cancer patients. Ramosetron's efficacy in this triple combination regimen has not been investigated.This prospective, multicenter, single-blind,randomized,phaseIIIstudycompares a combination of ramosetron, aprepitant, and dexamethasone (RAD) with a combination of ondansetron, aprepitant, and dexamethasone (OAD) to prove the noninferiority of RAD in controlling highly emetogenic CINV. Methods. Aprepitant and dexamethasone were orally administered for both arms. Ramosetron and ondansetron were intravenouslygiventothe RADandOADgroups.Theprimaryendpoint was no vomiting and retching and no need for rescue medication duringtheacuteperiod(day1);thenoninferioritymarginwas215%.