It appears to be the fashion at present to re-examine the effects of prolonged convalescence on the outcome of chronic diseases. This paper approaches this question in connection with the management of acute rheumatic fever. The study is based on observations in a particular setting, a military installation, which may limit the application to young males under closely controlled circumstances. The author considers that the prompt eradication of streptococci from patients with acute rheumatic fever by means of antibiotics may alter the familiar course of the disease as well as modify the severity of the acute attack. He also questions whether the prolonged and strict bed-rest customarily recommended is needed under the present circumstances where relapses due to recrudescence precipitated by streptococcal infections may be avoided. Under the circumstances which existed in the military installation where the study was conducted, prompt diagnosis and hospitalization, and early elimination of streptococci by penicillin, resulted in a more benign course of the disease and a shorter period of disability. However the incidence of valvulitis was not materially altered. It is the author's opinion that bed-rest beyond the period of acute carditis does not affect the final outcome and that the development of valvulitis may not be entirely prevented by any current method of therapy. He contends that earlier teaching, that premature physical activity leads to relapse and further heart damage, cannot be substantiated. Similar studies in children will have to support these suggestions before the traditional opinion can justifiably be reversed.