One hundred and nine patients over the age of 65 years with valvular heart disease have been reviewed. Of these, 57 patients were treated medically (medical group) and the remaining 52 patients underwent valve surgery (surgical group). Of the 57 patients who were treated medically, 46 (81%) were in NYHA Functional Class I or II, 7 were in Class III, and 4 were in Class IV. Among these, there were 8 deaths. The 5 year survival rate of the medical group, calculated by the actuarial method, was 90 +/- 5%. Eight patients had a nonfatal cerebrovascular accident. Of the 52 elderly patients who underwent valve surgery, 20 were in NYHA Functional Class II, 21 were in Class III, and 11 were in Class IV. Of these, there were 5 operative deaths (9.6%). Four patients died of postoperative low cardiac output syndrome and renal failure. One died of intraoperative aortic dissection. Of the 470 patients under the age of 65 years, there were 15 operative deaths (3.2%). Forty-one of the 47 hospital survivors have improved their cardiac functional classification, while 6 patients have remained in the same class as preoperatively. The average NYHA Class prior to operation was 2.7 improved to Class 1.3 after operation. The 3 year survival rate of the surgical group, calculated by the actuarial method, was 81 +/- 6%. Thus, the prognosis of asymptomatic elderly patients is good. Although operative mortality for the symptomatic elderly patients is relatively high, valve surgery can be performed with a satisfactory prognostic outlook.