Objective: Down syndrome is one of the most common chromosomal disorders. Congenital heart diseases in patients with Down syndrome are seen frequently and the most important cause of morbidity and mortality in this syndrome. In this study, the demographic characteristics, comorbid diseases and congenital heart anomalies of patients with Down syndrome admitted to our Pediatric Cardiology Department were evaluated.

Material and Methods: The data of 107 subjects with Down syndrome admitted to our Pediatric Cardiology Department between January 2010 and December 2015 were evaluated.

Results: Congenital heart diseases were presented in 77.5% of the patients with Down syndrome. There was a secundum atrial septal defect in 49.3%, ventricular septal defect in 33.7%, complete type atrioventricular septal defect in 18.1%, patent ductus arteriosus in 10.8%, and bicuspid aortic valve in 3.7%. There was pulmonary stenosis in one case, aorta coarctation in one case and Tetralogy of Fallot in one case. As regards an additional abnormality; there was hypothyroidism in 38.3%, visual impairment in 6.5%, hearing problems in 5.6%, and undescended testicle in 3.7% of the patients with Down syndrome. Cardiac defects were observed more frequently in patients with hypothyroidism than without hypothyroidism (p<0.05).conclusion: Congenital heart diseases are common in patients with Down syndrome. Even when there are no clinical signs and symptoms, cardiac evaluation of patients with Down syndrome provides early diagnosis and prevents the development of irreversible complications that may arise in the future

Keywords: Child, Congenital heart disease, Down syndrome