The mortality of heart failure patients with renal insufficiency is high, and these patients tend to develop diuretic resistance. Under these conditions, continuous hemodiafiltration (CHDF) is a possible alternative volume reduction therapy to diuretics. However, its efficacy and safety are not clear. Between April 2005 and March 2008, 248 patients with acute decompensated heart failure were admitted to the CCU of Kyoto City Hospital. Of those patients, 31 (20 volume overloaded heart failure, 11 cardiogenic shock) received CHDF therapy, and their weight loss, acute hemodynamic changes, and clinical outcome were assessed to evaluate the efficacy and safety of CHDF therapy. CHDF was performed for 6.5 +/- 6.5 days. There was no significant change in acute hemodynamics after CHDF initiation. In the volume overloaded heart failure (VH) group, significant weight loss was observed at 24 hours and 48 hours after CHDF initiation (P < 0.001). In-hospital mortality of the VH group and cardiogenic shock (CS) group were 10.0% and 54.5%, respectively. CHDF for acute decompensated heart failure (ADHF) is a safe, effective, and reliable volume reduction therapy for volume overloaded heart failure. Further investigation is required to assess the effectiveness of CHDF for cardiogenic shock.