As part of the Medicare Physician Extender Reimbursement Study, a mail survey was conducted of 5,572 physician extenders (PEs) to identify potential study participants. Analysis of survey results indicates that PEs are distributed disproportionately more often than physicians to primary care practices and to rural low income areas. However, there are substantial differences among types of PEs with regard to practice location and practice arrangement. The relationship between these findings and the distribution of other medical manpower and innovations is then discussed.