Giant coronary artery aneurysms (gCAAs) with a diameter exceeding 5 cm are extremely rare. The pathomechanisms and therapeutical measures in such cases have been controversial topics of discussion. Twenty-seven patients with gCAAs exceeding 5 cm in size described in the literature were evaluated. A case with multiple gCAAs at our department was included in the analysis. Apart from atherosclerosis of all coronary arteries, a large (1.5 2.5 cm) left anterior descending coronary artery aneurysm (CAA) and a gCAA (10.6 9.2 cm) originating from the right coronary artery, the latter causing recurrent myocardial ischaemia with the occlusion of the peripheral right coronary artery and compressing the right cardiac cavities, were the pathological findings in our 43-year old male patient. gCAAs predominantly develop at the proximal right coronary artery. The majority of these aneurysms develop secondary to atherosclerotic lesions in young patients. We performed a successful surgical excision of the right gCAA, tightening of the left anterior descending artery aneurysm and concomitant coronary artery bypass grafting. A pathological examination confirmed advanced atherosclerosis. Microbiological examinations could find no signs of infectious causes. CAAs bear a significant risk of severe complications and have a high risk of mortality. A more aggressive surgical approach should be recommended.