Cytokine-induced killer (CIK) cells show cytolytic activity against tumor. The purpose of this study was to evaluate the antitumor effect of dendritic cell (DC)-activated CIK cells in vitro and their clinical efficacy of DC-activated CIK cells in combination with chemotherapy (abbreviated below as chemotherapy plus DC + CIK) in patients with advanced non-small-cell lung cancer (NSCLC). A paired study was performed between 61 patients treated with chemotherapy alone (group 1) and 61 patients treated with chemotherapy plus DC + CIK cells (group 2). In group 2, 36 patients with adenocarcinoma and 18 patients with squamous cell carcinoma were analyzed for the survival rate. Compared to unstimulated CIK cells, DC-activated CIK cells significantly enhanced antitumor activity, increased the ratio of CD3(+)CD56(+) cells, promoted cell proliferation and lessened cell apoptosis. In the paired study, the 1- and 2-year overall survival rates in group 2 were 57.2 and 27.0 %, which were significantly higher than that of group 1 (37.3 and 10.1 %) (P < 0.05). There was no significant difference in the survival rate between the adenocarcinoma and squamous carcinoma patients in group 2. The present study suggests that DC-activated CIK cell has enhanced antitumor effects and chemotherapy plus DC + CIK cells improved the clinical outcomes of chemotherapy for advanced NSCLC patients.