Patients who undergo radiation therapy that includes the salivary glands frequently experience severe xerostomia. The standard of care for these patients who have natural teeth has become daily application of fluoride by means of custom-fabricated carriers. The purpose of this study was to determine patient compliance with fluoride gel application using carriers. Using a structured verbal questionnaire, we interviewed 76 patients who had completed radiation therapy for head and neck cancer. Thirty of these patients were seen regularly in the dental clinic of the Cancer Agency (group 1); the remaining 46 were not seen on a regular basis (group 2). Overall, 43% of patients reported using fluoride gel regularly (once a day). In group 1, 67% of patients used fluoride regularly, as did 28% of patients in group 2 (p = 0.001). There were no significant differences between the groups in frequency of toothbrushing and use of dental floss. Compliance with the use of fluoride in carriers was not associated with differences in other oral care measures in the two groups, which suggests that fluoride application in carriers achieves limited compliance in relation to daily oral health care measures. Regular follow-up of patients after radiation therapy is needed to assess their need for, and compliance with, daily fluoride application.