Objective: To compare the efficacy and safety of pemetrexed or gemcitabine combined with carboplatin in the treatment of elderly patients with advanced lung adenocarcinoma. Methods: From January 2010 to December 2011 in our hospital, 84 elderly patients(≥65) with stage Ⅲ b and Ⅳ lung adenocarcinoma were collected, and randomly divided into pemetrexed plus carboplatin group(PC) with 42 cases and gemcitabine plus carboplatin group(GC) with 42 cases. PC group was received pemetrexed 500 mg /m2d1 and carboplatin in the area under the curve(Auc) of =5 d2, whereas GC group was recieved gemcitabine 1000 mg/m2d1,8,and carboplatin at a dose of Auc=5 level d2. One treatment cycles were 21 days. The efficiency, adverse reactions and 1, 2 year survival rate were compared. Results: The total effective rates in PC group and GC group were 28.6% and 19%(P0.05) respectively. The disease control rates were 73.8% and 57.1%(P0.05). The median PFS were 11.8 and 10.2 months(P0.05).1 year survival rates were 52.3% and51.2%(P0.05). 2 years survival rates were 24.1% and 22.4%(P0.05). In the PC group,?leukopenia, anemia and thrombocytopenia were significantly lower than those in the GC group(P0.05). Conclusion: The efficacy of pemetrexed or gemcitabine combined with carboplatin in the treatment of elderly patients with advanced lung adenocarcinoma was roughly similar, but the former may be less adverse reactions. Therefore pemetrexed combined with carboplatin can be used as a safe and effective drug for clinical first-line treatment for the elderly patients with advanced lung adenocarcinoma.