Benzquinamide HCl, a new antiemetic agent, was studied in twelve healthy volunteers. Each subject received intravenously both benzquinamide (0.7 mg/kg) and placebo in a randomized, double-blind crossover manner. Cardiac output and arterial pressure, arterial blood gases, respiration (tidal volume and rate), and oxygen consumption were measured twice before drug administration and at 5, 10, 20 and 30 min after injection. Intra-arterial pressure increased significantly (P less than 0.005) at 5 min (12.6%) and 10 min (8.6%) following benzquinamide. Likewise, peripheral vascular resistance increased significantly (P less than 0.005) at 5 min (14.3%) and 10 min (8.8%) post-injection. Cardiac output, stroke volume and heart rate remained essentially unchanged. A significant increase (P less than 0.025) in respiratory rate was observed at 10 min (8.7%) and 20 min (12.6%) following benzquinamide. Values for the arterial Po2, Pco2, and pH showed no significant changes. It is considered that the effect of benzquinamide in increasing intra-arterial pressure is due to the increased peripheral vascular resistance.