This article reviews and updates the current literature concerning the assessment, diagnosis, and therapy of coronary disease involving the LMCA. Included is recent information regarding the natural history, congenital abnormalities, noninvasive diagnostic studies, and role of coronary bypass surgery and percutaneous coronary interventions in treating disease of the LMCA. At present, it remains that the LMCA is a difficult segment to assess angiographically. The use of noninvasive imaging does not specifically distinguish LMCA from other types of coronary disease. Coronary bypass surgery has a proven benefit in the treatment of disease of the LMCA. Currently, interventional procedures are limited by significant risks, and surgical treatment with coronary bypass surgery remains the therapy of choice.