To the Editor.— The article by Dr Allen1addresses an important issue. However, the data analyses as reported in Tables 1 and 3 of the article are based on a fallacy—that all physicians who list themselves in the American Medical Association's Physician Masterfile as practicing a certain specialty become eligible to join the major medical specialty society in that field. In obstetrics and gynecology, as in many other specialties, to be a fellow of The American College of Obstetricians and Gynecologists requires certification by the specialty board and to be a junior fellow requires involvement in a residency program accredited by the Accreditation Council for Graduate Medical Education or maintaining active-candidate board status after residency. Our own manpower studies over the years have identified a minimum of 10% of all obstetrics and gynecology physicians listed in the American Medical Association's Physician Masterfile as failing to meet these criteria.