In patients treated with radiation therapy for non-small cell lung carcinoma, positron emission tomography and computed tomography are commonly used to assess response to treatment. Seven rather small single-institution series have documented the ability of posttreatment positron emission tomography to predict local control and survival through measurements of [F] fluorodeoxyglucose uptake. The ability to make prognostic assessments using this information would be a major clinical breakthrough by allowing early alterations in patient management. Here, we review the current literature on the prognostic value of posttreatment [F] fluorodeoxyglucose uptake in patients treated with radiation therapy with or without chemotherapy for non-small cell lung carcinoma.