Cardiac surgery is a common treatment method for 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 three to seven 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. These symptoms may negatively affect their self-care ability and self-efficacy. The main aim of the study is to assess the level of knowledge among post CABG(Coronary Artery Bypass Grafting) patients and to find out the association between knowledge with the selected demographic variables like age, gender, marital status, education, occupation, dietary pattern, exercise, and bad habits. The study was non-experimental, descriptive research design with a quantitative research approach. The study was conducted in Sree Mookambika Institute of Medical Science, Kulasekharam. A sample of 30 post-CABG patients were selected by using the convenience sampling technique. The tools used for the data collection were demographic variables and a structured knowledge questionnaire. The data was analyzed and interpreted in terms of the objective, descriptive, and inferential statistics. The study findings show that 23.33% of the sample has average knowledge, 46.66% of the sample has a low level of knowledge, and 30% has a very low level of knowledge. There is a significant association between the level of knowledge and demographic variables such as marital status.