The method of DNA-cytometry was applied to examine patients presenting with nasopharyngeal malignancy. The results obtained in laboratory studies were compared with clinical observations and data of medical histories. It was shown that diploid and aneuploid nasopharyngeal tumours are represented in an equal proportion. The number of the latter tumours increased with the progress of the neoplastic process. The diploid and aneuploid tumours were characterized by the equally frequent occurrence of metastasis. The survivorship rate of patients presenting with diploid tumours during the first year after the onset of the disease was significantly higher than in the patients having aneuploid nasopharyngeal cancer. The results of the study indicate that DNA-ploidy can not be used as a predictor of the development of the neoplastic process in patients with nasopharyngeal cancer, nor does it have a predictive value for the evaluation of the efficacy of chemo/radiotherapy. Nevertheless, the data obtained may be useful for the selection of patients for the more intensive adjuvant therapy.