Docetaxel as single-agent therapy (100 mg/m2 and 75 mg/m2, every 3 weeks) produces response rates of 26% to 54%. Docetaxel has proven superior compared to best supportive care (BSC) in chemotherapy-naïve as well as in platinum pretreated patients. In addition, docetaxel is active in cisplatin refractory or resistant patients, producing responses ranging from 18% to 25%, implying a lack of cross-resistance between docetaxel and cisplatin, probably due to their different mechanisms of action. Furthermore, docetaxel is associated with significant prolongation of survival when administered as second line therapy, in pretreated patients with advanced NSCLC. Phase II studies of pemetrexed in previously untreated patients with NSCLC have demonstrated single agent response rates of 17% to 23%. A phase II study of pemetrexed in patients with advanced NSCLC, who had progressed during or within 3 months of completing first-line chemotherapy, demonstrated a response rate of 8.9% and median survival time of 5.7 months. Multivariate analysis established an association between an increased risk of severe pemetrexed toxicity and elevated homocysteine (folate and/or B12 vitamin deficiency marker) levels. Since December 1999, all pemetrexed-treated patients are required to receive folic acid and Vitamin B12. A recently reported phase III study compared pemetrexed with docetaxel as 2nd line therapy in patients with advanced NSCLC. Treatment with pemetrexed resulted in clinically equivalent efficacy outcomes, but with significantly fewer side effects compared with docetaxel.