Abstract Background We report the case of a white caucasian 63-year-old patient admitted to the clinic because of atypical angina and palpitations. Other comorbidities included hypertension, hyperuricemia and hypercholesterolaemia. He was admitted to a tertiary cardiac centre for deepened diagnostics of his complaints. Case summary Echocardiography revealed no pathology, but due to high Calcium Score (Agatston > 400 units), signs of arrhythmia during exercise and atypical angina complaints further investigations were performed. Invasive coronary angiography revealed stenosis up to 53% in the middle part of the right coronary artery and computed tomography angiography showed no left coronary artery, only malignant-coursed vessel, running from the proximal part of the right coronary artery. Single photon emission tomography findings allowed to come to a decision to not perform invasive treatment (coronary artery bypass grafting), due to acceptable perfusion and viability of the heart muscle. Discussion Single coronary artery is an extremely rare anomaly. This requires highly individualised diagnostic approaches, which include multiple imaging modalities, as each adds different information. While the only coronary vessel was narrowed in 53%, no significant ischemia was detected. Left ventricular function remained preserved.