The inadvertent ligation of the left pulmonary artery (LPA) is a rarely seen surgical complication that has been presented in the literature in a limited number of cases after patent ductus arteriosus (PDA) ligation surgery. Case Report: A PDA closure operation was performed on our patient, a 28-week-old preterm. In the postoperative follow-up, we identified on echocardiography taken on the same postoperative day that the ductus space was still present. On CT angiography, we determined that not only was the ductus space still continuing, but, in addition, ligation of the LPA had been performed inadvertently. An LPA reconstruction operation was performed on the patient 46 days after the first operation. However, owing to severe tissue damage in LPA, LPA reperfusion did not occur in the postoperative period. Conclusion: Although inadvertent ligation of the left pulmonary artery during PDA ligation surgery is rarely seen in patients who have undergone closure surgery, this complication should be kept in mind in the postoperative follow-up period. Patient findings such as physical examination, lung angiography and postoperative echocardiography should be assessed with this in mind.