Background and objectives: Iodine is the key element required for the production of thyroid hormones, and its deficiency, even mild, is harmful in pregnancy, causes deleterious effects on fetal brain development and other complications of pregnancy. Iodine deficiency is best managed by ensuring adequate intake of iodine rich foods and can be prevented by upgrading the knowledge of prenatal mothers regarding importance of iodine rich food through STP. Present study attempts to evaluate the effectiveness of STP on knowledge regarding importance of Iodine rich food among prenatal mothers at selected PHC, Ramanagara District. Methods: The research approach used in the present study is experimental approach with pre experimental design. Respondents were selected through purposive sampling technique. The pre-test was conducted on 50 prenatal mothers in 9 sessions by using structured interview schedule followed by implementation of STP and post test was conducted after 7 days to find out the effectiveness. Results: Majority of the respondents were from 18-22 years, completed secondary school education, were housewives, were Hindus, were belonged to nuclear family, were primigravida, were in second trimester of pregnancy, had family income below Rs. 5000, were vegetarians, 2% were had the habit of tobacco chewing. Major information is from mass media. Regarding effectiveness of STP, the overall mean knowledge score in the pre-test was 37.9% and 76.7% in the post test with enhancement of 38.9% and it is significant at 5% level. Analysis of demographic variable showed there is significant association between gravid, type of family, food habits with knowledge score at 5% level (P>0.05). Interpretation and conclusion: Overall findings of the study showed that there is inadequate knowledge among prenatal mothers regarding importance of Iodine rich food and STP was significantly effective in the enhancement of knowledge of prenatal mothers, which in turn contribute to improve their offspring’s health.