To the Editor: The article by Landefeld et al. on the value of autopsies (May 12 issue)* makes an error commonly made by those advocating more autopsies. The mere fact that a procedure in medicine yields knowledge does not mean that the procedure should be done more often. There are costs to all procedures, and the real question is whether the information yielded is worth the price paid to obtain it. For example, it should be new information to few physicians that fungal infections, pulmonary emboli, and retroperitoneal hemorrhage are missed clinically (as reconfirmed by Landefeld et al.). Our diagnostic. © 1988, Massachusetts Medical Society. All rights reserved.