Objective: To assess the effect of cilazapril treatment on several hemodynamic parameters during handgrip maneuvers in patients with congestive heart failure. Cilazapril, an ACE inhibitor with high affinity, has been shown to be highly effective against a variety of vascular disorders. The effectiveness of isometric handgrip exercise on changes of cardiovascular hemodynamic parameters before and after cilazapril treatment in patients with congestive heart failure is unknown. Methods: The study population included 30 patients (16 male, 14 female) with mean age of 65±18 years. The effects of handgrip maneuver on hemodynamic parameters were studied by right heart catheterization and Doppler echocardiography. Results: Heart rate (HR) and mean arterial pressures (MAP) increased significantly after handgrip maneuver (from 95±6 beats/min to 101±12 beats/min; from 109±15 mm Hg to 118±19 mm Hg, p<0.05 respectively). Pulmonary capillary wedge pressure (PCWP), pulmonary artery systolic (s) and diastolic (d) pressures (PAP), cardiac index (CI), right ventricular systolic and diastolic pressures (RVPs and RVPd), left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF) did not change after handgrip maneuvers (p>0.05). On the other hand, PAPs and PAPd, RVPs and RVPd, MAP and HR (p<0.05) decreased significantly during handgrip maneuvers after cilazapril treatment. However PCWP and CI, LVEF, RVEF did not change after treatment (p>0.05). Conclusion: Cardiovascular response to handgrip maneuver may be a marker of failure to respond to compensatory mechanisms. Cilazapril treatment was associated with significant improvement in hemodynamic parameters during handgrip stress test, the mechanisms of which are increased sympathetic and renin-angiotensin system activation, and altered vascular tonus.