School-based immunization is a program of the Department of Health to eliminate emergence of vaccine-preventable diseases among school children. In Mahayag, immunization rate remained low even after mop-up and it was noted that no health education on school-based immunization was conducted among parents and guardians. Based on the survey conducted, knowledge deficiency on school-based immunization, on the importance of immunization, safety and side-effects of vaccines and misconceptions on immunization, was evident in the community. This study was done to determine the effect of lecture with pamphlet on the knowledge of parents and guardians of Grades 7 students regarding school-based immunization in a public high school in Mayahag, Zamboanga del Sur. The study utilized a pre and post interventional research design conducted in Mahayag School of Arts and Trade using convenience sampling. Knowledge of 56 respondents was assessed using the 20-item, true or false questionnaire. Data collection was done before and immediately after the educational intervention. Data for knowledge were analyzed using t-test and McNemar’s test for item analysis. Immunization acceptance rate was assessed through the actual immunization practice. Results show that there was a significant improvement in the mean knowledge scores of the respondents from 13.04 before the intervention to 16.07 after the intervention at p-value of 0.00. The immunization acceptance rate is at 91.1%. This study concludes that lecture with pamphlet is effective in improving knowledge of parents and guardians regarding school-based immunization among Grade 7 students and there is a good acceptance rate for school-based immunization after the intervention. Comparison on the effect of health education conducted by nurse/midwife versus doctors is recommended

Keyword: lecture pamphlet immunization Mahayag