To investigate the effects of ketamine on the hemodynamics decreased by fentanyl-diazepam, twenty-five patients were randomly assigned to three groups. In all patients fentanyl (10 ug/kg) diazepam (0.2 mg/kg) was intravenously administered, and then patients in group 1 recevied saline only, group 2 and group 3 recevied 1 and 2 mg/kg of ketamine, respectively. Hemodynamic parameters were obtained before and 5 minutes after durg in each group. In group 1, fentanyl-diazepam produced a decrease in heart rate (HR:17%), mean arterial pressure (MAP:27%), cardiac index (CI:40%) and sroke volume index (SVI:14%), and a increase in mean pulmonary arterial pressure (MPAP:27%) and pulmonary capillary wedge preasure (PCWP;25%), but no significant change in central venous pressure (CVP) and systemic vascular resistance index (SVRI). Patients in group 2 had decreases in HR(16%), MAP(10%), CI(10%) and SVI(16%), and decrease in MPAP(21%), PAWP(21%), PCWP(26%), CVP(58%) and SVRI(24%), but theae hemodynamic changes were no significant difference compared to those of group 1 except a bit increase in CVP and SVRI. In group 3, HR(11%), MAP(11%), CI(23%), and SVI(13%) were decreased, but MPAP(14%), PCWP(14%), CVP(69%) and SVRI(26%) were increased and these values were no difference compared to those of group 2. These results demonstrated that ketamine did not significantly affect the hemodynamics decreased by fentanyl-diazepam except CVP and SVRI were increased by ketamine. Base on this study, the author suggeeted that the mechanism of cardiovascular depression caused by diazepam-fentanyl might to be the result of myocardial depression, ketamine produced its sympathomimetic actions primarily by direct stimulation of central nervous system, and ketamine might to be unuseful to improve the hemodynamics to patients with cardiovaseulsr depreseion caused by fentanyl-diazepam.