OBJECTIVES: To describe resource utilization and costs associated with treating surgically managed non-small-cell lung cancer (NSCLC) patients in Ontario, Canada; to compare characteristics and average costs of patients treated with adjuvant therapy to surgery alone; and to compare resource utilization and costs across healthcare regions.  METHODS: A population-based retrospective cohort study of surgically resected NSCLC patients, diagnosed from Ontario Cancer Registry between 2004 and 2006, was identified using administrative healthcare data.  Patients were followed for four years from date of surgery (to represent the cohort immediately affected by the change in clinical practice -- recommended adjuvant cisplatin-based treatment). Cost estimates (2001 CAN dollars) were derived from administrative data and the literature.  RESULTS: Patients who received adjuvant chemotherapy in addition to surgery were younger and had a less severe burden of co-morbid disease than patients treated with surgery alone (p<0.001). Geographic variation was found with respect to age, Charlson score, and socioeconomic status. Rates of chemotherapy, the proportion of patients who received any imaging scans, hospitalizations, specialist visits, emergency room visits, mean number of imaging scans, general physician visits, and blood transfusions all varied significantly among geographic regions. The average cost of a patient treated with surgery and adjuvant chemotherapy was $36,617.70 and was significantly higher than the average cost of a patient treated with surgery alone ($29,071.60) (p<0.0001). Among regions, the average cost of patients treated with chemotherapy was similar, while the average cost of patients treated with surgery alone varied significantly (p=0.0008). CONCLUSIONS: Differences exist in the average cost of treating a resectable NSCLC patient with surgery and adjuvant chemotherapy in comparison with surgery alone. This phase IV population-based study demonstrates a similar cost per patient as evidenced in the randomized controlled trials.  Understanding why these patients incur higher average costs is important with respect to delivering cost-effective treatment.