The effect of radiation on speech and swallowing function was assessed for 18 patients surgically treated for oral and oropharyngeal cancer. Nine patients received surgical intervention and postoperative radiation therapy, and nine received surgery only. Patients were matched regarding percentage of oral tongue resected, percentage of tongue base resected, locus of resection, and method of reconstruction. Speech and swallowing function was assessed before and at 1, 3, 6, and 12 months after surgery following a standardized protocol. Speech tasks included an audio recording of a brief conversation and of a standard articulation test; swallowing function was examined with videofluoroscopy. Statistical testing indicated that overall speech function did not differ between the irradiated and nonirradiated patients. Irradiated patients had significantly reduced oral and pharyngeal swallowing performance, specifically, longer oral transit times on paste boluses, lower oropharyngeal swallow efficiency, increased pharyngeal residue, and reduced cricopharyngeal opening duration. Impaired function may be the result of radiation effects such as edema, fibrosis, and reduced salivary flow. Increased use of tongue range-of-motion exercises during and after radiation treatment may reduce the formation of fibrotic tissue in the oral cavity and may improve pharyngeal clearance by maintaining adequate tongue base-to-pharyngeal wall contact.