Breast cancer is a major public health issue and most commonly diagnosed for women worldwide. Breast cancer accounts for 22.9% of all cancer in women. It is estimated nearly 1.7 million new cases of cancer occurred worldwide in 2012. This represents about 12% of new cancer cases and 25% of all cancers in women. The objective of the study was to assess the level of knowledge on breast cancer among antenatal mothers. The study was conducted at mamandur SRM rural health centre, Kancheepuram district. A total of 50 samples were selected using non-probability purposive sampling technique. The tool used for the study comprises of 2 sections, section A- Demographic Data (which includes: age, religion, type of family, educational status, area of residence, income) and section B- a structured questionnaire developed by the investigator which indicates 25 questions to assess the level of knowledge on breast cancer among antenatal mothers. The findings of the study revealed that 32 (64.0%) of antenatal mothers had inadequate knowledge, 18 (36.0%) of antenatal mothers had moderate knowledge and none of them are having adequate knowledge. Therefore adolescent girls and women of all age group must be able to recognise the signs and symptoms of breast lump to facilitate rapid identification and transport of patient to the hospital.