Propofol (P) is increasingly used as a sedative during regional anesthesia. Providing titratable sedation and rapid recovery, it can compromise hemodynamic stability. However, in combination with ketamine (K), it provides stable hemodynamics during total intravenous anesthesia, avoiding emergence phenomena. We compared the efficacy, respiratory and hemodynamic profiles, and side effects of these two sedative regimes in patients undergoing spinal anesthesia. Forty patients, ASA physical status I and II, undergoing urologic or orthopedic procedures were randomly assigned to one of two groups (n = 20 each). Group 1 (P + K) received initial doses of 0.4 mg/kg P, 0.1 mg/kg K, followed by an intravenous infusion of 1.2 mg x kg(-1) x h(-1) and 0.3 mg x kg(-1) x h(-1), respectively. Group 2 (P) received bolus 0.5 mg/kg and infusion 1.5 mg x kg(-1) x h(-1). Subsequent infusion rates were titrated to a predetermined sedation level using a 5-point score. Heart rate, arterial pressure, respiratory rate, oxygen saturation end-tidal CO2, and oxygen requirements were recorded. Sedation scores were similar for both groups. There was no difference in total propofol requirements between Group 1 (146 +/- 94 mg) and Group 2 (137 +/- 52 mg) (mean +/- SD). Mean arterial pressure was significantly higher in the P + K group, e.g., 91 mm Hg (86-94) vs 75 mm Hg (69-83) at 30 min (mean +/- SD). Administration of vasopressors and fluids as well as recovery and emergence phenomena were similar between groups. Although the described additive effect of propofol and ketamine was not confirmed, the combination conferred hemodynamic stability during spinal anesthesia.