Cardiac surgery is among the commonly used methods to treat cardiovascular diseases. it leads to a decrease in patients’ self-care ability and causes some changes in the physical and psychological functionality of the individual. Because patients who have undergone cardiac surgery are usually discharged home within 3 to 7 days, they may experience a series of symptoms at home after discharge, such as pain, wound, infection, oedema, dyspnea, arrhythmia, constipation, loss of appetite, and sleep disturbance, and these symptoms may negatively affect their self-care ability and self-efficacy. The main aim of the study to assess the level of knowledge among post CABG patients, to find out the association between knowledge with the selected demographic variables like age, gender, marital status, education, occupation, dietary pattern, exercise, Bad habits. The study was Non experimental descriptive research design with quantitative research approach. The study was conducted in Sree Mookambika institute of medical science, Kulasekharam. 30 samples were selected by using convenience sampling technique. The tools used for the data collections were demographic variables, and structured knowledge questionnaire. The data was analyzed and interpreted in terms of the objective, descriptive and inferential statistics. The study findings are 23.33% sample has average knowledge, 46.66% sample has low level of knowledge, 30% has very low level of knowledge. There is significant association between the level of knowledge and demographic variables such as marital status.