The paper entitled "Sustained Bacteremia in Patients with Prosthetic Cardiac Valves" by Sande and his colleagues in this issue of the Journal focuses attention on and suggests an approach to resolution of a clinically important, difficult and now quite common diagnostic dilemma. Failure to recognize the exact nature of this dilemma may lead to serious errors of commission or omission. It is clear from the data presented that the development of bacteremia shortly after implantation of a prosthetic valve in the heart must not always be equated with infection of the prosthesis. Unawareness of this fact may lead to surgical . . .