 This is a two-arm, parallel, open-label, Phase 2 multicenter study of pemetrexed as first line combination therapy with either cisplatin or carboplatin in the palliative setting of stage IIIb and IV non-small cell lung cancer patients. Approximately 130 patients will be included in about 15 centers in Germany and randomized to one of the above treatment regimens in a 1:1 ratio. Chemotherapy will be administered over a maximum of six cycles with a standard length of 21 days. Primary objective will be the Progression Free Survival Time of patients as assessed in both treatment arms. 