Stage III non-small cell lung cancer (NSCLC) treatment is evolving. There are several choices available regarding which chemotherapy to use and how to optimally combine them with radiotherapy. Gemcitabine (Gemzar, Eli Lilly and Company, Indianapolis, USA) is a chemotherapeutic agent with activity in NSCLC, and preclinical studies have shown that gemcitabine is a potent radiosensitizer. These two characteristics make gemcitabine a potential option when treating patients with stage III NSCLC. This review article describes the efficacy and tolerance of gemcitabine when combined with radiation in those patients. Gemcitabine used concurrently with radiation, as an induction regimen before radiation, and as a consolidation regimen after radiation is reviewed.