To determine the electrocardiographic features associated with left main coronary artery(LMCA) or Left main equivalent coronary artery (LMEQ) obstruction. Early detection of LMCA or LMEQ coronary artery is very important in selecting the appropriate treatment strategy as delay in diagnosis can have catastrophic consequences. We randomly selected 41 angiographically proven LMCA or LMEQ coronary artery obstruction patients and manually analyzed their ECG retrospectively. ST-segment elevation was significant in lead aVR (51.2%), and lead V1 (48.8%). ST depression was significant in lead V5 (48.78%), and lead V4 (36.5%). The combination of ST elevation in aVR with ST depression in precordial leads was significant in aVR and V5 combination (39.0%), and aVR and V4 combination (34.1%). LM with TVD had the highest incidence (34.1%) followed by LM with SVD (29.3%), LM with DVD (19.5%) and LMEQ only (17.1%). ST-segment elevation in lead aVR and/or V1 can give indication of LMCA occlusion. Careful reading of ECG is vital in the diagnosis of LM or LMEQ obstruction.