One-hundred-and-eighty-nine episodes of infective Endocarditis were seen in 177 patients in the Green Lane Cardiology Unit over a 18-year period. Hospital survival was 79% and 13-year actuarial survival was 47%. A number of factors including the underlying cardiac lesion, infecting organism, clinical features and surgical intervention were related to outcome. No patient with extreme heart failure survived without operation. Hospital survival in patients with severe heart failure was 69% (9/13 patients) where surgery was carried out before completion of antibiotic treatment, and 40% (6/15 patients) where the antibiotic course was completed. Survival was 53% in patients who still had a fever after one week of antibiotic treatment and 96% if the temperature was normal. In 61% of patients with a fever at one week, extended infected pannus was present compared with 6--10% where the temperature was normal. In patients undergoing operation before completion of antibiotics, the surgical mortality was higher but neither the incidence of recurrence of endocarditis nor the need for re-operation was increased. We believe that better results will be achieved with a policy of surgical intervention when signs of infection and heart failure have not settled within one week of treatment.