Since the implementation of National Health Insurance (NHI) program in 1995, hospital executives and medical professional groups have constantly complained about the dilemma in recruiting physicians for certain specialties. To confirm this unbalanced supply in medical manpower, we reviewed and analyzed data on the patterns of demand and training in medical specialties and the growth of practitioners before and after launching NHI. Changes, in numbers of practitioners and health care institutions and reimbu rsement claims between 1992 and 1997,were compared by specialty to determine whether the NHI payment policy has exerted influence on medical graduates in their career decision. The results showed significant variations amongst all specialties in both monetary reimbursement and number of claims filed to NHI. A significant correlation between the payment policy and the number of resident applications, by specialty, among medical centers was observed as well. Newly established clinics were thus varied by spec ific specialty. Compared with the number of clinics available by specialty in 1992, the largest growth in specialty until 1997 was Rehabilitation (93.3%), followed by Family Medicine (22.1%), Pediatrics, Ophthalmology, ENT and Dermatology. There was only 1.0% of growth in surgery. The NHI payment schedule did affect both medical graduates' career decisions and the growth of clinics in selected specialties. Although financial incentive was not the only factor influencing the medical manpower structure among all specialties, its impact can not be overlooked. The results suggest that the NHI should carefully review and consider a balanced development across all specialties before any change or reform of the payment system can be undertaken.