Systemic inflammation after cardiac surgery using cardiopulmonary bypass (CPB), is closely associated with postoperative organ dysfunction. We evaluated the efficacy of continuous hemodiafiltration (CHDF) in controlling postoperative organ dysfunction, focusing on serum inflammatory substances and organ protection. We enrolled 14 patients with postoperative circulatory collapse. The mean age of patients was 71 years. Heart valve surgery was performed in 9 patients, coronary artery bypass grafting in 5 and graft replacement of the thoracic aorta in 2. The mean CPB time was 297±28 min. CHDF was initiated on the first or second postoperative day in 12 patients. A polysulfone membrane dialyzer and nafamostat mesilate were used for CHDF. 1) On blood examinations, serum IL-6 and IL-8 concentrations decreased 12 h after the initiation of CHDF (216±50→92±27 pg/dl, 71±23→30±7 pg/dl, respectively). Serum aldosterone decreased at 12 h (144±20→104±21 pg/ml). Four hours after the initiation of CHDF, systemic blood pressure significantly increased from 94±6 to 123±6 mmHg. The systemic vascular resistance index significantly increased from 1,431±137 dyn·sec·cm^-5·m² to 1,893±167. Urine volume significantly increased from 42±38 to 100±29 ml/h. Serum creatinine decreased from 2.1±0.3 mg/dl to 1.7±0.2 mg/dl on the second day. Respiratory function had significantly improved at 24 h. Early induction of CHDF reduced serum inflammatory substances, resulting in quick circulatory recovery without organ failure.