The purpose of this study was to assess free-flap viability in patients treated for recurrent head and neck cancers. A 10-year retrospective review identified 121 patients who had had prior head and neck cancers extirpated for cure, who subsequently presented with documented recurrent cancers that were removed, and who then underwent reconstruction with free flaps. The charts of these patients were reviewed for patient demographics, tumor types, location, flaps used for reconstruction, size of area requiring reconstruction, length of operation, previous radiation, and all postoperative morbidity and mortality. The time to recurrence ranged from 21/2 months to 21 years. The majority of tumors treated were squamous cell carcinomas (n = 82). Most of them were located intraorally (n = 75). Radiation therapy had been delivered to 88 patients before their free-flap reconstructions. In this series, 31 percent of all patients required additional surgery for complications, 14 percent of free flaps were lost, and 4 percent of patients died within 30 days of their operation. The significant findings were that a flap that was >4 cm in diameter was related to flap loss (p = 0.03 by the chi2 method) and that flap loss was related to operative times greater than 11 hours (p = 0.03 by the chi2 method). It was concluded that recurrent head and neck cancers with large postextirpation defects that required prolonged operative times yielded a significantly high tendency toward flap failure.