Background: coronary artery diseases affect millions of patients in the world which cause a lot of complications up to death. by very simple non-invasive method like ECG we can predict and early diagnose and even localize very serious lesion in coronary angiograghy in patient with chronic stable angina and this is the target of our research. Aim of Work: this study aimed to detect the diagnostic value of ST segment and T wave changes in lead AVL in patient with chronic stable angina. Methods: this was a prospective observation study that was done from June 2017 to July 2018 and it included 200 patients presented to Alhussin University Hospital or referred to us from other secondary hospitals with chronic stable angina. All patients were subjected to full history, clinical examination, ECG and coronary angiograms with focusing on ST segment and T wave changes and analyses and localized the lesions in coronary angiograms and their relationship to previous ECG changes. Results: mean age in patients in our study was 55.89 years old with 77% males and 23% females. The most common risk factor was HTN. There was a relationship between ST-T wave changes in lead AVL in patient with chronic stable angina with a moderate agreement to mid LAD lesion 78% and to lesser degree LCX then RCA and LM. Conclusion: according to the previous results of our research, inverted T wave in lead AVL in chronic stable angina corresponds angiographically to tight mid left anterior descending coronary artery lesion.