Granisetron is a highly selective serotonin 5-HT(3) receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting. The transdermal granisetron system delivers continuous granisetron (3.1 mg/day) into the systemic circulation (via passive diffusion) for up to 7 days. In a large phase III trial in cancer patients receiving multi-day (3-5 days) moderately or highly emetogenic chemotherapy, transdermal granisetron applied 24-48 hours prior to chemotherapy and remaining in place for 7 days was noninferior to oral granisetron 2 mg once daily administered for 3-5 days 1 hour prior to chemotherapy. Efficacy was assessed according to the proportion of patients achieving complete response (no vomiting and/or retching, no more than mild nausea, no rescue medication) from the first day, until 24 hours after the start of the last day, of administration of the chemotherapy regimen. In a phase II trial in patients with cancer receiving single-day, moderately-emetogenic chemotherapy, transdermal granisetron applied at least 24 hours prior to chemotherapy and removed after 5 days was as effective as a single oral dose of granisetron 2 mg in achieving total control (no nausea, no vomiting/retching, no use of rescue medication and no study withdrawal) during the delayed (24-120 hours; primary endpoint) period after chemotherapy. Transdermal granisetron was generally well tolerated in clinical trials, with few adverse events being treatment related.