Reducing post-operative complications from lung surgery is critical. We explored if intra-operative bronchioalveolar lavage would reduce post-operative respiratory complications such atelectasis, pneumonia, and mucous plugging. BAL is well-researched as a diagnostic tool but its use as a protective procedure is not well studied. We conducted a retrospective cohort study of 291 patients who underwent routine BAL intraoperatively during lung surgery in the last 3 years as well as a comparison group of 215 patients who did not receive intra-operative BAL. This group of 506 patients fit the inclusion criteria of having undergone lung resection. Exclusion criteria were as follows: lack of one-lung ventilation, concurrent other surgery. All the surgeries took place at Health Sciences Centre in Winnipeg. 34.9% (n = 75) of patients in control group and 37.1% (n = 108) of the cases had some type of post-operative complication as classified by the Ottawa TM&M. Narrowing down to only respiratory complications (pulmonary and pleural), 20.5% (n = 44) of controls and 25.5% (n = 73) of cases had complications. When looking at only pulmonary complications, 7.4% (n = 16) of the controls and 9.6% (n = 28) of the cases had pulmonary complications. We saw that patients who received BAL prophylactically had a similar incidence of pulmonary complications compared to the control group (9.6% and 7.4% respectively). However, multivariable analysis shows that current smokers benefited greatly from prophylactic BAL where there was a reduction in pulmonary complications.