OBJECTIVES: I. Determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of gemcitabine when administered with paclitaxel and fluorouracil with concurrent hyperfractionated radiotherapy in patients with advanced and/or recurrent head and neck cancer. II. Determine the MTD and DLT of gemcitabine as a single agent with radiotherapy in these patients. III. Determine the efficacy of concurrent chemoradiotherapy in terms of time to progression, pattern of failure, and overall survival in patients with measurable disease. IV. Determine gemcitabine and fluorouracil pharmacokinetics in these patients.