NKT cells are activated by a specific ligand, alpha-Galactosylceramide (aGalCer), and exerted a strong anti-tumor activity. We performed a phase I/II study of aGalCer-pulsed DCs in patients with advanced or recurrent non-small cell lung cancer (NSCLC) to obtain more findings about safety, immune responses and anti-tumor responses. Patients with advanced NSCLC or recurrent lung cancer refractory to the standard therapy were eligible. aGalCer-pulsed DCs were intravenously administered four times. Immune responses were monitored weekly by a flow cytometry analysis and an enzyme-linked immunospot assay. Additional follow-up was performed to clarify the prognosis and cause of death. Seventeen patients completed the study protocol and were considered suitable for immunological analysis. No severe adverse event related to the treatment was observed. After the injection of aGalCer-pulsed DCs, increased numbers of IFN-g producing cells in the peripheral blood were detected in 10 patients (58.8%). Five cases remained as stable disease (SD), and the remaining twelve cases were evaluated as progressive disease (PD). The estimated median survival time (MST) of the 17 cases was 18.6 months (range, 3.8 to 36.3 months). Thus the administration of aGalCer-pulsed DCs was well tolerated and was accompanied by the successful induction of NKT cell-dependent immune responses. These results are encouraging and warrant further evaluation for survival benefit of this immunotherapy.