Aims: Coronary arterial abnormalities, congenital and acquired, may co-exist with structural congenital malformations of the heart. This study analyses information obtained from coronary angiography in grown-up patients with congenital cardiac disease undergoing cardiac catheterisation. Methods and Results: We studied 448 patients, of whom 181 (40%) had selective coronary angiography. This was undertaken as a routine measure in 165 (37%), and because of clinical indications in 16 (4%). Aortic root angiography was carried out in 107 (24%). Coronary arterial abnormalities were demonstrated in one-third of those undergoing selective angiography, and in 69% of those with a clinical indication for angiography, compared with 30% who had a routine procedure. In those patients undergoing aortography alone, abnormalities were recognized in 17%, while the angiographic images were inconclusive in 24%. In the remaining 59%, no abnormality was apparent, but only the proximal coronary arteries could be seen clearly. In total, congenital abnormalities of the coronary arteries were found in 11% of the patients, acquired lesions were demonstrated in 5%, and surgically acquired lesions in 2%. Conclusion: Routine coronary angiography during catheterization of grown-up patients with congenital heart disease revealed a high incidence of abnormalities of the coronary arteries. Selective injection into the arteries had a higher sensitivity than aortography. Consideration should be given to performing routine coronary arteriography during invasive investigation of patients with congenital cardiac disease, as it provides useful and often unexpected information, which may be valuable for the interpretation of symptoms and the planning of subsequent surgery.