The 5-HT3-receptor antagonists, which are regarded as the 'antiemetic gold-standard', are used for prophylaxis against chemotherapy- and radiotherapy-induced emesis. At equally effective doses, the 5-HT3-receptor antagonists have been shown to demonstrate broadly equivalent clinical antiemetic activity and safety. However, the pharmacology of granisetron suggests that it may have an improved side-effect and tolerability profile, a lower risk of drug interactions and a longer duration of action than other 5-HT3-receptor antagonists. The high affinity of granisetron, coupled with the insurmountable antagonism displayed at 5-HT3 receptors, is thought to underlie its good clinical efficacy.