Congenital unilateral absence of the pulmonary artery (UAPA) is an extremely rare heart defect. If present in the isolated form, i.e. without concomitant diseases, its symptoms are non-specific and include respiratory infections, lower exercise tolerance or dyspnea. Additionally, hemoptysis or pulmonary hypertension may occur. Two case reports of patients with diagnosed congenital absence of the left branch of pulmonary artery have been presented. In the first case, the reason for performing diagnostic tests was the chest wall deformity, while in the latter – frequent respiratory infections.