PURPOSE: To perform a comprehensive cognitive function (CF) assessment in patients who were relapse free after curative intent radiotherapy (RT) or chemoradiotherapy for squamous cell carcinoma of the head and neck. METHODS AND MATERIALS: Patients underwent neuropsychological tests to assess their objective CF; completed questionnaires to assess subjective CF, quality of life, and affect; and underwent blood tests to assess hematologic, biochemical, endocrine, and cytokine status. Retrospectively, the dosimetry of incidental radiation to the brain was determined for all patients, and the dose intensity of cisplatin was determined in those who had undergone chemoradiotherapy. RESULTS: A total of 10 patients were enrolled (5 treated with radiotherapy only and 5 with radiotherapy and cisplatin). The mean time from the end of treatment was 20 months (range, 9-41). All patients were able to complete the assessment protocol. Of the 10 patients, 9 had impaired objective CF, with memory the most severely affected. The severity of memory impairment correlated significantly with the radiation dose to the temporal lobes, and impaired dexterity correlated significantly with the radiation dose to the cerebellum, suggesting that these deficits might be treatment related. Patients receiving cisplatin appeared to have poorer objective CF than patients receiving only RT, although this difference did not achieve statistical significance, likely owing to the small sample size. Consistent with the published data, objective CF did not correlate with subjective CF or quality of life. No association was found between objective CF and patients' affect, hematologic, biochemical, endocrine, and cytokine status. CONCLUSION: Neuropsychological testing is feasible in squamous cell carcinoma of the head-and-neck survivors. The findings were suggestive of treatment-related cognitive dysfunction. These results warrant additional investigation.