Background: There is some evidence that cisplatin-based chemotherapy doublet regimens are more efficacious than the less toxic carboplatin-based doublet regimens for advanced non-small cell lung cancer (NSCLC) but little evidence of effectiveness in elderly cancer patients treated in the usual care setting. We estimated differences in survival and post-treatment morbidity between first-line cisplatin-based and carboplatin-based doublet regimens in elderly Medicare patients with advanced NSCLC. Methods: We identified 13,406 elderly Medicare patients who were diagnosed with stage IV NSCLC between 1995-2009 in SEER regions and treated with either a cisplatin-based doublet chemotherapy regimen or a carboplatin-based doublet chemotherapy regimen in the subsequent six months. Using propensity score weighting, we balanced the two treatment cohorts with respect to observable attributes. We then estimated survival and toxicity according to treatment. Results: Overall patients treated with cisplatin-based doublets lived nearly two weeks longer on average than patients treated with carboplatin-based doublets (i.e., 7.4 months vs. 7.0 months, p=0.05) survival differences were not appreciated in subsets of patients with adenocarcinoma or squamous carcinoma. Patients treated with cisplatin-based doublets were slightly more likely than those patients treated with carboplatin-based doublets to be hospitalized (i.e., 42.9% vs 39.8%, p<0.01) and use intensive hospital-based care. Conclusions: Among elderly Medicare patients with advanced NSCLC, those treated with first line cisplatin-based doublet chemotherapy regimens lived slightly longer than those treated with carboplatin-based doublet regimens, but also utilized more hospital-based care following treatment. The difference in overall survival is not clinically significant, and does not appear to justify the added toxicity.