The purpose of this study was to find out health education activities of the 435 school nurses in the secondary schools in Seoul. A questionnaire was sent by mail on March 11, 1985 and received a total of 252 responds till April 4, 1985. Among them, 230 were included in final analysis. Those of 22 school nurses who have worked not more than one year were excluded. The results of the findings obtained of this study are summarized as follows ; 1. An average number of health education activities carried out by the school nurses turned out to be 31.7 times/nurse/year. 2. The practice rates of health education activities by contents of health education were revealed as follows ; in parasite disease 89.6%, hepatitis 89.1% physical examination 87.3%, influenza 84.3%, etc. Health education on drinking and smoking, drug abuse were the lowest rate as 37.8% and 40.9%. 3. The practice rates of health education by the school nurses according to the health education methods were shown as follows ; instruction by the teacher 90.9%, bulletin boards in the classroom 73.0%, message to home notices 72.6%, etc. 4. Difficulties in carrying out health education programs by the school nurse were analysed according to Likert's five point scale. The scores on item to the no availability of teaching tools and tips were 3.90, no availability of audiovisual aids 3.80, lack of understanding from the school principals 3.30, insufficient time of the school nurse 3.26, no guidance or improper form of health education material 3.20, lack of knowledge of educational method 3.18. As a conclusion of this study, the development of the supporting system to health education activities and programs for improvement of school health education is strongly needed from policy making level.