Background of the study : Antenatal checkup is the systematic medical supervision of women during pregnancy and it includes education, counseling, screening and treatment to monitor and to promote the well-being of the mother and fetus. Antenatal check up is the key entry point of a pregnant woman to receive broad range of health promotion and preventive services which promote the health of the mother and the baby. India being developing countries contribute 26% global burden MMR with annually 136000 women dying annually. Proper antenatal checkup and diagnostic is one of the important ways to reduce the maternal and child mortality and morbidity. Therefore present study is to evaluate the effectiveness of structured teaching programme on knowledge regarding importance of antenatal checkup and diagnostic measures among primi mothers. Material and methods : Evaluative research approach and quasi experimental one group pre test and post test design was adopted. Convenient sampling method was used to select the 60 primi antenatal mothers in selected community area at Bangalore. Demographic performa and structured questionnaire were used to collect the data from the sample and the data were analyzed by descriptive and inferential statistics. Results : The results showed that in pre test all primi mothers 60(100%) are inadequate knowledge. Over all pretest mean 8.84, SD 1.65 and mean percentage 22.1%. In post test, 40(66.7%) primi mothers had adequate knowledge, 20 (33.3%) had moderately adequate knowledge. In post test over all mean 31.89, SD 1.32 and mean percentage 79.7%. The paired't 'test value 36.4 of overall score of knowledge was significant at P<0.01 level. There was a significant association between the post test demographic variables such as education, monthly income, types of family and do you receive information among primi mothers. Conclusion : Therefore it is proved statistically and concluded that structured teaching was effective in the improvement of knowledge on primi mothers, regarding antenatal check up and diagnostic measures. Antenatal check-up and diagnostic is very important for every pregnant woman should take in to great consideration. The study recommended an emphasis on health education for mother's awareness of the importance of regular antenatal checkup and diagnostic measures to health centre and hospital during pregnancy. There is a need to motivate women to utilize maternal care services which are freely available in all government health setup.