This study was conducted from march 20 through April 20, 1992, jn order to figure out the factors affecting behavior of the people on environmental health. 1, 261 people were selected by sampling from Seoul, Pusan, Taegu, Taejon and Kwangju. Questionnaire forms were prepared and the persons selected were-interviewed by trained interviewers. The data collected were analyzed in order to determine factors affecting kowledge, attitude and practice on environmental health in major cities in Korea. The major results are as follows: 1. The people who got high KAP score were found not to practice what they know. The people who got lower scores were found to use their knowledge in practical life. 2. Correlation between knowledge, attitude, and practice (KAP) on environmental health was statistically significant (p < 0.001). 3. The levels of KAP on environmental health affected by variables of gender and marital status were statistically significant (p < 0.01). 4. Variables of education, occupation, religion and economic status affected the levels of KAP significantly (p < 0.01). 5. The levels of KAP on environmental health by variables of health education on environmental health were statistically significant (p < 0.001). 6. The levels of KAP of the people on environmental health by demographic variables showed a reverse relation statistically (p < 0.001). 7. The levels of KAP of the people on environmental health had correlation with education level and the KAP level had correlation with knowledge (p < 0.001). 8. The KAP levels of the people on environmental health had correlation with environmental health education (p < 0.001). 9. The total variables affecting KAP of the people on environmental health had 14% variance and environmental health education was the highest($eta$=0.23827), education level was the next($eta$=0.12442), and economic status was ($eta$=-0.06970), age ($eta$=-0.06710) and print media ($eta$=0.06539). 10. The variables most affecting KAP of the people on environmental health were environmental health education(r=0.2980) and education(r=0.2419) and the next were age, marital status, religion, electronic media, print media, place of birth and gender. 11. The most important variable affecting KAP level of the people on environmental health was education level.