Granisetron has been shown to exert a beneficial therapeutic effect in the prophylaxis and treatment of acute nausea and vomiting due to chemotherapy. However, limited data regarding its efficacy in the prevention and treatment of delayed emesis are available. A total of 532 patients entered this multicenter double-blind study, aimed at comparing the efficacy and safety of intramuscular (i.m.) granisetron with that of i.m. granisetron plus dexamethasone. Complete response and total control were evaluated for 3 days following the first 24 h after cisplatin administration in two groups of patients: 262 treated with granisetron 3 mg i.m. daily (plus placebo), and 265 with granisetron at the same dose plus dexamethasone 8 and 4 mg twice daily. The rate of complete response was 58.0% in the granisetron group and 78.9% in the granisetron plus dexamethasone group over days 1-3 (p<0.01). Similarly, over the same period total control was 44.7% with granisetron alone and 65.3% with granisetron plus dexamethasone (p<0.01). Local and systemic tolerability of the i.m. therapy with granisetron were satisfactory. In conclusion, granisetron plus dexamethasone showed good protection against delayed emesis due to emetogenic chemotherapy.