Between January 1978 and December 1984, 141 cases of acute native valve endocarditis were treated surgically in the Department of Thoracic and Cardiovascular Surgery of the Pitié Hospital. The diagnostic criteria of acute native valve endocarditis were the duration of treatment (antibiotic therapy for less than 40 days), the characteristic operative appearances of the lesions, and the results of anatomo-pathological examination of the excised valves. The infecting organism was not isolated in 35% of cases. The aortic valve was the commonest site of infection (65.2% with a high incidence of abscess of the aortic ring, irrespective of the causal organism. The operative mortality was 5.6%. This depended mainly on the preoperative haemodynamic status of the patient. The duration of antibiotic therapy prior to surgery did not seem to be relevant. The 3 years survival rate was 78%. The secondary reoperation rate was 7%. There was a higher incidence of secondary perivalvular regurgitation in patients who had previously had an abscess of the aortic ring.