The objective of this study is to analyse the costs and benefits of the Expanded Programme on Immunization under the Ministry of Public Health in Thailand from 1977 to 1989. The target vaccines are DTP, OPV, MEASLES, BCG, and T (pregnant woman) which prevent Diphtheria, Tetanus, Pertussis, Measles, Tuberculosis and Tetanus Neonatorum, respectively. The costs are calculated from the related budgets, cost of vaccines, and international supports. The direct benefits estimated here are confined only to those accrued to the Ministry of Public Health, in terms of savings in treatment costs of cases prevented. The social indirect benefits are calculated on the expected life earnings of deaths prevented. Cases prevented are estimated from a suitable econometric model in two conditions : with, and without EPI. Deaths prevented are estimated from the number of cases prevented and the average case fatality rate. This study shows that Measles vaccine has the highest benefit/cost ratio which is 55.30. The benefit/cost ratios of OPV, DTP, and T (pregnant woman) are 4.58, 2.62, and 2.56, respectively. The benefit/cost ratio of BCG vaccine cannot be obtained due to its vague benefit. The overall benefit/cost ratio of EPI programme is 3.96

M.Econ. จุฬาลงกรณ์มหาวิทยาลัย ปี 2535