OBJECTIVES: The burden of comorbid illness is known to be higher among lung cancer patients and its also shown to impact survival outcomes.  However, the influence of comorbidity on in-hospital surgical outcomes among lung cancer patients remains unknown.  Therefore, this study examined the effect of comorbidity on risk of postoperative complications, prolonged hospitalization, and in-patient death among lung cancer patients following surgery. METHODS: A retrospective analysis of hospital discharge data from the 2011 Health Care Utilization Project - Nationwide Inpatient Sample (HCUP-NIS) database was performed.  Discharges of patients who underwent surgery for lung cancer during 2011 were identified. Information about patients and hospitals characteristics were obtained. Comorbidities were identified and used to calculate Charlson comorbidity index score. Patients were then divided based on these scores into four groups: 0, 1, 2, and ≥3. Multivariate logistic regression analyses was used to examine risk adjusted association between comorbidity score and the study outcomes. RESULTS: We identified 19,564 patients’ discharges that meet our inclusion criteria. Compared to patients with no comorbid conditions, patients with one or more comorbid conditions saw a two-fold increase in the risk of post-operative complications (p<0.001). The risk of prolonged hospitalization was also higher among patients with a comorbidity score of 1, 2, or ≥3, compared to patients with a comorbidity score of zero (p<0.001). Higher comorbidity burden also increased the risk of in-patient death by three folds (p<0.001). CONCLUSIONS: In-hospital outcomes among lung cancer patients following surgery are negatively impacted by presence of comorbid illness.  Post-operative morbidity and mortality among these patients may be reduced if their comorbid conditions are managed effectively.