Postoperative emetic symptoms (nausea, retching, and vomiting) frequently occur in women undergoing general anesthesia for abdominal hysterectomy. In a previous report by us, granisetron, a selective serotonin receptor antagonist, was more effective than the traditional antiemetics, droperidol and metoclopramide, for the treatment of postoperative emetic symptoms in this population.The aim of this study was to determine the optimal dose of granisetron for the treatment of emetic symptoms following abdominal hysterectomy.This randomized, double-blind, placebo-controlled, dose-ranging study was conducted at Toride Kyodo General Hospital (Toride, Japan). Female patients aged 33 to 66 years experiencing postoperative emetic symptoms after abdominal hysterectomy were eligible for the study. Patients received IV granisetron at 1 of 4 doses (10, 20, 40, or 100 μg/kg) or placebo; they were then observed for 24 hours. Emetic symptoms and the need for a rescue antiemetic were recorded by nursing staff, who were blinded to treatment assignment.A total of 100 patients (mean [SD] age, 45 [7] years [range, 33–66 years]) were enrolled (n = 20 in each group). No significant differences in patient demographic characteristics were observed between the groups. The number of patients in whom complete control of postoperative emetic symptoms, defined as being free of emetic symptoms and not needing rescue antiemetic medication for 24 hours after study drug administration, was established was significantly greater in 3 of the granisetron groups than in the placebo group (6 patients [30%]): granisetron 10 μg/kg, 7 patients (35%; P= NS); granisetron 20 μg/kg, 17 patients (85%; P = 0.001); granisetron 40 μg/kg, 17 patients (85%; P = 0.001); and granisetron 100 μg/kg, 16 patients (80%; P = 0.002). No clinically significant adverse events attributable to the study drug were observed in any group.In this study of patients who experienced emetic symptoms after undergoing general anesthesia for abdominal hysterectomy, granisetron at doses ≥20 μg/kg was effective in the treatment of established postoperative emetic symptoms.