Purpose: To analyze the prospectively collected health-related quality-of-life (HRQOL) data from patients enrolled in two Radiation Therapy Oncology Group randomized Phase III head and neck cancer trials (90-03 and 91-11) to assess their value as an independent prognostic factor for locoregional control (LRC) and/or overall survival (OS). Methods and Materials: HRQOL questionnaires, using a validated instrument, the Functional Assessment of Cancer Therapy-Head and Neck (FACT-H&N), version 2, were completed by patients before the start of treatment. OS and LRC were the outcome measures analyzed using a multivariate Cox proportional hazard model. Results: Baseline FACT-H&N data were available for 1,093 patients and missing for 417 patients. No significant difference in outcome was found between the patients with and without baseline FACT-H&N data (p = 0.58). The median follow-up time was 27.2 months for all patients and 49 months for surviving patients. Multivariate analyses were performed for both OS and LRC. Beyond tumor and nodal stage, Karnofsky performance status, primary site, cigarette use, use of concurrent chemotherapy, and altered fractionation schedules, the FACT-H&N score was independently predictive of LRC (but not OS), with p = 0.0038. The functional well-being component of the FACT-H&N predicted most significantly for LRC (p = 0.0004). Conclusions: This study represents, to our knowledge, the largest analysis of HRQOL as a prognostic factor in locally advanced head and neck cancer patients. The results of this study have demonstrated the importance of baseline HRQOL as a significant and independent predictor of LRC in patients with locally advanced head and neck cancer. © 2008 Elsevier Inc. All rights reserved.