The hydrochloride salt of a 2-piperazinylbenzimidazole-derivative serotonin type 3 (5-HT3) receptor antagonist with antiemetic activity. Lerisetron specifically binds to 5-HT3 receptors, located peripherally on vagus nerve terminals and centrally in the chemoreceptor trigger zone (CTZ) of the area postrema, which may result in suppression of chemotherapy-induced nausea and vomiting.