Aim. To evaluate the functionality of a bovine monocusp in surgery for tetralogy of Fallot.Methods. We analyzed the results of surgical treatment in the early postoperative period in eight infants and one year after surgery in seven infants (age range, 0–12 months; mean weight = 7.5 ± 2.3 kg). We used echocardiography to evaluate the residual pressure gradient between the right ventricle and the pulmonary artery, the degree of regurgitation on the pulmonary valve after surgery and to calculate Z-score and the fibrous ring diameter of the pulmonary valve in the late follow-up period. The degree of insufficiency was assessed by the width and depth of the regurgitation flow using the color Doppler mode.Results. The pressure gradient on the eve of discharge did not exceed 25 mmHg for any patient. Pulmonary valve regurgitation was mild in four patients and moderate in the remaining patients. Seven children passed the observation one year after surgery. In one case, we discovered a right ventricle outflow tract obstruction. In other cases, the systolic pressure gradient did not exceed 25 mmHg. Four patients in the late follow-up period had severe valve regurgitation. Despite such valve insufficiency, the leaflet mobility in the bovine jugular vein patch was normal.Conclusion. Early postoperative results for reconstructive surgery to repair tetralogy of Fallot with a bovine monocusp were promising. However, long-term results are comparable with those using other materials. The mobility of the native leaflet remains full even a year after surgery. Consequently, we have positive prospects in material improvement for making patches with native monocusps. Received 14 May 2020. Revised 8 June 2020. Accepted 10 June 2020. Funding: The study did not have sponsorship. Conflict of interest: Authors declare no conflict of interest. Author contributionsConception and study design: A.A. Svobodov, E.G. Levchenko, V.T. KostavaData collection and analysis: G.S. Netalieva, M.V. ZelivyanskayaStatistical analysis: E.G. Levchenko, M.V. ZelivyanskayaDrafting the article: A.A. Svobodov, V.S. RasumovskyCritical revision of the article: V.S. RasumovskyFinal approval of the version to be published: A.A. Svobodov, E.G. Levchenko, G.S. Netalieva, V.T. Kostava, M.V. Zelivyanskaya, V.S. Rasumovsky