Atrioventricular canal defect (AVCD) is a congenital heart defect, which occurs in 2.9 % of all congenital heart defects (CHD) and is characterized by a wide variety of anatomical forms and often don't have clear cardiac manifestation. Untreated AVCD may lead to the development of pulmonary hypertension.Aim. To determine clinical features of AVCD in children, considering variable anatomical forms of the pathology and its association with genetic pathology.Materials and methods. Patients history and outpatient statistic records of children with AVCD, who were admitted to Lviv Regional Children's Hospital from September 1999 till January 2016 have been analyzed (n=84).The aspects of clinical manifestation of AVCD without associated pathology have been identified (n=48). Clinical manifestation of complete (n=36) and incomplete (n=12) AVCD and clinical manifestation with and without Down syndrome have been discussed.Children with AVCD were divided into two groups: A – children with complete (n=36) and B – with incomplete (n=12) form of AVCD. Group A was divided into A1 – with trisomy 21 (n=14), A2 – without genetic pathology (n=22).Results. In group А2 – 36,36±10,26 % and in group В – 50±14,4 % children were asymptomatic. Dyspnea, increased sweating during feeds, growth retardation and frequent respiratory viral infections during early childhood period were leading symptoms. Most frequent auscultation findings were accent of II heart sound over the pulmonary artery and 2-3/6 systolic murmur over left sternal border. According to echocardiographic examination mitral valve insufficiency was predominantly of mild grade, tricuspid insufficiency and pulmonary hypertension was diagnosed in group А2 with the frequency of 9,09±6,13 %).Conclusions: The absence of clinical features in group A2 and B 36,36±10,26 and 50,00±14,40 respectively, saturation levels 92,36±0,49 % in patients without genetic pathology and 95,25±0,40 % with incomplete AVCD provide a need to adopt protocol of children examination with saturation level under 95 % and compulsory echocardiographic diagnosis within the first month of life.