Dissertation describes the case of 7.5-year-old boy with recanalization of the ductus arteriosus. In this patient treated because of the non-Hodgkin lymphoma during the chemotherapy the respiratory failure occurred and mechanical ventilation was required. After the respiratorotherapy in the controlled echocardiography examination the patency of previously closed ductus arteriosus, was described. There was no description of the similar case in available references.