To determine whether pre-operative nutritional status and post-operative time on mechanical ventilation, as well as others factors, are correlated with post-operative complications (general or pulmonary) in patients undergoing elective thoracic surgery. A prospective study was conducted, involving 71 patients undergoing elective pulmonary resection. The data collected pre-operatively included gender, age, smoking status, pre-albumin level, lymphocyte count, and body mass index. The peri-operative data included type of surgery and surgical time, as well as post-operative time on mechanical ventilation. Post-operative complications were found to correlate with low pre-albumin concentration, type of resection, surgical time, and post-operative time on mechanical ventilation. Surgical time and post-operative time on mechanical ventilation were also implicated in the post-operative pulmonary complications observed in 22 (30.99%) of the patients studied. Our results suggest that pre-albumin concentration, type of surgery and surgical time, as well as post-operative time on mechanical ventilation, serve as predictive indices of post-operative complications in patients undergoing elective pulmonary resection. In the analysis of the post-operative pulmonary complications, statistically significant correlations were found between such complications and increases in surgical time or post-operative time on mechanical ventilation.32489-94