The aim of the study was to assess the relationship between intraoperatively observed macroscopic pathologic findings in the left lung and the chosen clinical factors. The factors analyzed in the study were the following: neonatal gestational age and body weight, the age of the neonate at the time of surgery, the history of intrauterine infection and/or presence of active infection in the neonate, the history of ibuprofen treatment, and intraoperative diameter of the arterial duct.Material and methods. The authors included a group of 126 preterm infants with body weight less than 1000 g undergoing surgical treatment for PDA in the 2nd Department of Cardiac and General Pediatric Surgery between January 2000 and May 2006 and analyzed the macroscopic intraoperative left lung appearance.The average body weight of the neonates who participated in the study was 765.2 g, with the average gestational age 25.68 Hbd. According to the results of intraoperative macroscopic lung assessment, the neonates were classified into one of the following three groups:0 - normal lungs or partially stiff lungs with emphysema focuses,1 - limited macroscopic findings, focuses of limited atelectasis, lung congestion,2 - severe pathologic findings in the pulmonary tissue, pulmonary hematomas, bleeding pulmonary surface, disseminated atelectasis, liver-like pulmonary tissue.In the study, the statistical analysis of the relationship between pathological pulmonary findings (groups 0, 1, 2) and investigated factors was performed by the comparison of mean values (or median) of the investigated factor in the analyzed groups. The Kruskal-Wallis and the Mann-Whitney tests were used dependent of the analyzed factor. Additionally, for chosen factors (the infection presence and PDA diameter), their relationship with the lung macroscopic appearance was assessed with the use of the Spearman test.Results. The pathological findings in the lungs were observed in the majority of the neonates (54%). The statistical analysis did not show any relationship between the pulmonary disorders and the majority of investigated factors.Conclusions. 1. The authors found that a duct diameter of ≥ 4 mm correlates with the development of more severe disorders in the pulmonary tissue. 2. The authors emphasized the good results of surgical treatment of PDA and the lack of death in the perioperative period in that group of patients.