The Family Planning Program has been intensively implemented in Korea by the national policy since 19 62. However, the desired effective results were not fully obtained by many reasons such as the shortae of qualified workers, lack of eligible women's cooperation and understanding of the importance of family planning etc.. The field family planning workers is classified into two categories along the gouernmental personnel order; the senior field worker and the assistant field worker. The former is qualified licensed nurse and the latter same as the former of a certified nurses-aid. These family planning worker's roles are somewhat in change not only in field education, distribution of contraceptions, administrating mother's class of assistant field workers but also responsible for the senior field workers such as recording, reporting and keeping statistics. Therefor, the desired success of family planning programming in Korea depends on family planning worker's professional abilities and activities in the field. In aiming to study on professional knowledge of the above two kinds of family planning workers, the following results were obtained through a field survey with questionnairs done as of October, 1970 in Kyonggi-Do. 1. Working term of the family planning workers in average were less than two years. The younget the assistant Field workers were, the earlier they left job. 2. The assistant field workers selected their job in order to the superficial rather than implernenting job itself. 3. Most of the workers either in the health center or in the Up-Myun had a better understanding concern- ing with their job; contraceptive methcds, maintenance of equipment and drug keeping, and other admini- strative procedures, etc.. 4. They had relatively better understanding and sufficient knowledge about contraception itself appli- cation of it's methods and side effects in detail too, but less knowledges for the care after. 5. It was hard to Find out any differences in administrative knowledge and demographic understanding. 6. It is fully agreed upon that the lenger the worker have experienced with the program, the more skilful she applied. 7. The worker who had training whether pre-service or inservice are working more effectively than the untrained. 8. The fundamental demographic knowledge is recommended to obtain for the workers in Kyonggi-Do.