Marfan syndrome is an autosomal dominant genetic disorder that affects connective tissue and is caused by mutations in the fibrillin 1 gene present at chromosome 15. Aortic aneurysm is its main complication, and along the dilation of the aorta root and its descending portion (60–100%), with secondary aortic insufficiency, it increases risk of acute aortic dissection and death. Coronary artery anomalies affect between 0.3% and 1.6% of the general population and are the second leading cause of sudden death in young adults, especially if the anomalous coronary passes through aorta and pulmonary artery. The anomalous origin of the left main coronary artery in the right Valsalva sinus has a prevalence of 0.02%–0.05% and is commonly related to other congenital cardiac anomalies, such as transposition of great vessels, coronary fistulas, bicuspid aortic valve, and tetralogy of Fallot. Its association with Marfan syndrome is not known, and there is no previous report in the literature. We describe here a case of a female with Marfan syndrome diagnosed with symptomatic anomalous origin of the left coronary artery in the right Valsalva sinus.