The purpose of this study was to determine the efficacy and safety of a maintenance immunotherapy regimen administered to patients with recurrent/metastatic squamous cell carcinoma of the head and neck (RMHN) who showed clinical benefit from docetaxel, ifosfamide, and cisplatin chemotherapy (DIP). Every 4 weeks, patients with RMHN received 60 mg/m(2) docetaxel on day 1, and 1200mg/m(2) ifosfamide and 20mg/m(2) cisplatin on days 1 to 4. Low-dose subcutaneous interleukin-2 and oral 13-cis-retinoic acid were administered as maintenance immunotherapy to patients who showed a clinical benefit (complete or partial response, disease stability). The primary end point was response; secondary end points were progression-free survival, overall survival, toxicity, and evaluations of lymphocytes, natural killer cells, and serum vascular endothelial growth factor (VEGF). After a median follow-up of 22 months, 263 courses of chemotherapy were administered to the 54 patients. The overall response rate was 59%. Forty-two patients (78%) had a clinical benefit and received 185 courses of maintenance immunotherapy. Median progression-free survival and overall survival were 11.1 and 21.8 months, respectively. Statistically significant, progressive increases in lymphocytes and natural killer cells and a decrease in VEGF were observed in patients treated with maintenance immunotherapy. The toxicity was relatively well tolerated and caused no death. Outpatient administration of DIP, followed by low-dose interleukin-2 and 13-cis-retinoic acid, was generally well tolerated and showed promising activity against RMHN. Longitudinal changes in lymphocytes, natural killer cells, and VEGF might be useful biomarkers for response and survival.