['To evaluate response and survival according to (18)F-fluoro-2-deoxy-glucose uptake at presentation in patients with gefitinib-treated non-small cell lung cancer.', 'We retrospectively analyzed 84 positron emission tomography/computed tomography findings. Patient characteristics, response rates, and survivals were evaluated according to the maximum standardized uptake value (SUV) of primary tumor. The cutoff value of SUVs was obtained from receiver operating characteristic analysis.', 'The response rate (RR) was higher for never-smokers (41%) than ever-smokers (9%; P=0.001). Patients with adenocarcinoma showed higher RR than those with other tumor histopathology (35% versus 9%; P=0.009). The SUV was significantly lower in patients who were never-smokers (P=0.005), patients with adenocarcinoma (P<0.001), and female patients (P=0.017). Patients with a low SUV showed higher RR compared with those with a high SUV (53% versus 18%; P=0.003). Prolonged progression-free survival was observed in patients with low SUVs compared with those with high SUVs (median, 33.1 weeks versus 8.6 weeks; P=0.003). While controlling for performance status, smoking history, and pathology, the high SUV conferred unfavorable outcome (hazard ratio, 2.3; P=0.012). In terms of overall survival, a low SUV was associated with favorable outcome in univariate analysis (P=0.011). Patients with a low SUV showed prolonged survival in multivariate analysis (P=0.043).'] Does 18F-fluoro-2-deoxy-glucose uptake predict clinical outcome in patients with gefitinib-treated non-small cell lung cancer?