The number of trainees produced by a residency program must relate directly to manpower needs in a specialty, not to the service needs of the training institution. In order to avoid geographic maldistribution of specialists, it is preferable id determine correct trainee output on a regional basis and combine such information inductively to determine overall national needs. A model fur determination of the number of residents appropriate lo train in obstetrics and gynecology by 1985 in the University of Utah program has been constructed in the setting 0f regional requirements. Components of this model include detailed population growth forecasts at the county level, consideration of the impact of increased urbanization, agespecific data for attrition of regional specialists by death or retirement, and estimation of the proportion of regional requirements to be met by the University of Utah program on the basis of distribution data of previous graduates.