Administration of chemotherapy concurrently with radiation therapy theoretically improves local control by sensitizing the tumor to radiation, while simultaneously treating systemic disease, albeit at the expense of greater local toxicity. Two large phase III studies suggest improvement in both local control and survival with concurrent chemoradiotherapy as compared with sequential chemotherapy followed by radiation for patients with stage III NSCLC. Although rates of nonhematologic toxicity were higher on the concurrent arms, median survival time trended toward superiority in the concomitant chemotherapy plus daily radiation arm compared with the sequential arm.