To investigate the timing of surgery in active infective endocarditis, the data of 54 patients, consecutively operated for this reason from September 1973 to May 1989, were analysed. Native valves were involved in 31 patients (57%): the aortic valve in 22, the mitral valve in 6, and both valves in 3 cases. Prosthetic valves were involved in 23 patients (43%): the aortic valve in 14, the mitral valve in 7, and both valves in 2 cases. There were no significant differences between involvement of native or prosthetic valves and mortality, morbidity, or consequences of morbidity. No significant correlation was found between causative microorganism and mortality, morbidity, or consequences of morbidity. The indication for operation was cardiac failure in 15 patients (28%), ongoing infection in 24 (44%) or a combination of these in 15 (28%). Major embolization occurred in 12 patients (22%) and affected women more than men (p = 0.05). Hospital mortality was 8 (15%). Morbidity involved 15 more patients; structural deterioration of the valve prosthesis occurred in 1 patient; nonstructural dysfunction of the valve prosthesis occurred 11 times in 10 patients; anticoagulation-related hemorrhage involved 2 patients (1 with nonstructural dysfunction of the valve prosthesis); endocarditis was diagnosed in 3 patients. The consequences of these morbid events concerned 14 patients; reoperations were done 9 times in 8 patients; mortality was valve related in 6 cases. Because 2 more patients died during the course of the study, total late mortality was 8. Probability of survival 5 years after operation was 72% (95% cl 56-83) and at 10 years 47% (95% cl 21-70). Probability of event-free survival at 5 years was 53% (95% cl 37-67) and at 10 years 32% (95% cl 13-53). Mortality was significantly higher when cardiac failure was the indication for operation (p = 0.04). Mortality was higher in the earlier part of the series (p < 0.005). Patients were operated earlier in the latter part of the series (p < 0.03) Irrespective of the causative microorganism, "early" in surgery for active infective endocarditis can be defined as the moment that cardiac failure or infection persists or progresses, despite adequate medical (antibiotic) therapy.