Hypoplastic coronary artery disease (HCAD) is a rare coronary artery anomaly that may be the cause of sudden death. It can involve a single or all coronary arteries. This anomaly may cause circulatory insufficiency leading to myocardial infarction. HCAD has no symptoms or may exhibit cardiovascular signs like syncope, dyspnea, chest discomfort, or dizziness. It is often diagnosed at autopsy, and early diagnosis is made with a coronary angiogram. We report HCAD as the cause of the sudden death of a 25-year-old female with a history of loss of consciousness following exertion. On autopsy, all the coronary arteries' lumen was narrowed with thin vessel walls. Histopathological examination shows an underdeveloped and missing muscular layer of the left anterior descending and circumflex coronary arteries' vascular wall. Many cases of HCAD diagnosed by radiographic imaging in living patients have been reported in the literature, but a structural anomaly of coronaries leading to HCAD has not been reported. We report a case of HCAD describing the histopathological examination findings of the vascular wall of coronary vessels illustrating the structural difference.