The results of surgical treatment of active native infective endocarditis in 24 patients were analyzed. Fifteen of 24 (63%) patients were successfully cured by operation. Three of the 8 patients with severe cardiac failure who underwent emergency operation died of low cardiac output syndrome and bleeding early postoperatively. One of the 6 patients with late death had preoperative cerebral embolism and died of multiple organ failure. Five of them had annular infection. Among 6 patients with annular infection, 3 patients who had Staphylococcus epidermidis and Gram negative bacterium as a causative microorganism had a short duration within 4 weeks from the onset to operation. Two died suddenly in the long-term period after surgery because of prosthetic valve detachment. The second operation were required for other 4 patients because of prosthetic valve endocarditis or perivalvular leakage. Three of them were lost from low cardiac output syndrome. These findings suggested that delayed surgical intervention may be a major causative factor resulting in high surgical mortality. For patients with active native infective endocarditis, an early aggressive operation should be considered prior to congestive heart failure and the destruction of the annulus.