We conducted a double-blind, randomized crossover study to compare the toxicity and antiemetic efficacy of the 5-hydroxytryptamine3 receptor antagonist batanopride with that of metoclopramide in 21 chemotherapy-naive patients receiving at least 70 mg/m2 cisplatin. The study was terminated when hypotension was observed following the infusion of batanopride at other institutions testing similar drug schedules. Although we observed no hypotension following treatment with batanopride in this trial, we did note asymptomatic prolongation of the corrected QT interval (QTc), PR interval, and QRS complex on the EKG in the batanopride arm. Of 15 evaluable patients, 8 experienced less than or equal to 2 episodes of emesis within 24 h of the first batanopride infusion, whereas 9/15 subjects experienced less than or equal to 2 emetic episodes following the administration of metoclopramide. Overall, the evidence suggests that this dosing schedule for batanopride may be too toxic for clinical use.