BACKGROUND Single coronary artery is a rare condition characterized by the origin of a coronary that supplies the entire heart from a single coronary ostium. METHODS A 45-year-old woman with an altered exercise testing was addressed to a computed tomography coronary angiography (CTCA) to rule out coronary artery disease (CAD). METHODS CTCA examination showed the absence of the right coronary artery (RCA). The left anterior descending artery and the left circumflex artery (LCX) presented regular origin and course and LCX provided the posterior interventricular artery and the posterolateral artery. METHODS As CTCA highlighted the absence of potentially life-threatening features related to coronary anomaly, no surgical treatment was advised. RESULTS The patient was dismissed, kept under pharmacological control and monitored over time. CONCLUSIONS CTCA is the first-choice imaging modality in patients with ECG abnormalities properly allowing the differential diagnosis between CAD and congenital heart disease.