Objective:To evaluate the efifcacy and adverse reactions of pemetrexed as the ifrst-line treatment in elderly patients with advanced non-squamous non-small-cell lung cancer (NSCLC). Methods:The elderly patients with advanced non-squamous NSCLC received pemetrexed as the ifrst-line treatment were retrospectively analyzed. All of them were intravenously injected 500 mg/m2 pemetrexed, and 21 days were as one cycle. The efifciency was evaluated every two cycles till the disease progressed or sever adverse reactions occurred. The condition of adverse reactions as well as ifnal outcome were observed. Results: Eighty-seven patients were enrolled in the research, totally receiving 392 cycles of chemotherapy, and the mean for 1 patient being 4.5 cycles. After 2 cycles of chemotherapy, partial response (PR) and stable disease (SD) were respectively 39 and 18 cases. The response rate and disease control rate were 44.8%and 65.5%, respectively. The median overall survival (OS) of all patients was 16.1 months, and median progression-free survival (PFS) was 3.2 months. Twenty-ifve patients completed 4 cycles of chemotherapy, and 32 patients completed 6 cycles of chemotherapy at least. The median OS of patients>4 cycles of chemotherapy was 17.4 months, while those≤4 cycles was 13.6 months, and the difference had statistical signiifcance (χ2= 4.374, P= 0.036). The major adverse reactions included myelosuppression, fatigue and gastrointestinal reactions, mainly at grades 1~2. No treatment-related deaths occurred. Conclusion:The efifciency of pemetrexed is deifnite as the ifrst-line treatment in elderly patients with advanced non-squamous NSCLC, and the incidence of adverse reactions is low. The prognosis of patients is associated with cycles of pemetrexed chemotherapy.