BACKGROUND AND PURPOSE: Induction chemotherapy prior to definitive concurrent chemoradiotherapy (CCRT) is a promising treatment option for unresectable head and neck cancer (HNC). In the postoperative setting, the efficacy of such an approach with adjuvant chemotherapy (AdjCT) followed by postoperative CCRT is unclear. MATERIALS AND METHODS: Forty-one postoperative patients with stage III-IV (M0) HNC enrolled on 3 consecutive phase II clinical trials were retrospectively analyzed. Twenty-five of the patients were treated on a protocol which included AdjCT with carboplatin and paclitaxel prior to postoperative CCRT (AdjCT group). Sixteen were treated on protocols with similar postoperative CCRT but without AdjCT (control group). CCRT consisted of paclitaxel, 5-fluorouracil, hydroxyurea, and twice-daily radiotherapy. RESULTS: After a median follow-up of 72 months, there were no locoregional failures (LRF) or distant metastases (DM) in the AdjCT group. In the control group, there were 2 LRF and 2 DM. The 5-year risk of disease recurrence was 0% in the AdjCT group, compared to 28.9% in the control group (p=0.0074). No patients had disease progression during AdjCT, and all proceeded to postoperative CCRT without delay. CONCLUSIONS: Adjuvant chemotherapy after surgery followed by CCRT may be a treatment strategy associated with favorable disease outcomes in locoregionally advanced HNC. These results pose a hypothesis which warrants further investigation.