A 61-year-old female was diagnosed with cT2N1M0 adenocarcinoma in the right lung. Following resection of the right middle lobe and dissection of the second group of lymph nodes in July 2007, she was found to have pN2 disease, and carboplatin plus paclitaxel was administered as postoperative chemotherapy. Recurrence was found and gefitinib was administered as first-line chemotherapy. While the patient was followed on an outpatient basis, dysgeusia and headache developed in March 2009. As multiple brain metastases were confirmed by contrast-enhanced computed tomography, cranial irradiation (30 Gy in 10 fractions)was administered. Upon improvement of the patient's status to a level treatable by chemotherapy, a new second-line chemotherapy with pemetrexed was started. Since then, the patient has been followed on an outpatient basis and has currently completed 21 courses of chemotherapy. No recurrence has been observed thus far. The results suggest that pemetrexed is an effective agent for the treatment of brain metastases from lung adenocarcinoma.