Patients with stage III non-small cell lung cancer (NSCLC) frequently progress either within the irradiated field or systemically, due to uncontrolled microscopic dissemination present before the time of initial diagnosis. The use of combined modality therapy has led to improved survival rates in recent years. In particular, the use of cisplatin and vinblastine as induction chemotherapy is supported by two large randomized clinical trials. Nevertheless, the large majority of patients still die of progressive disease, thus providing a rationale for the integration of new active agents into the overall treatment plan of these patients. Gemcitabine has demonstrated significant single-agent activity in NSCLC. In addition, preclinical and early clinical data indicate that it is a powerful radiation enhancer. Clinical trials investigating this drug with concurrent radiation therapy in NSCLC are reviewed.