Fifteen patients with head and neck carcinoma were treated with irradiation (14-70 Gy telecobalt). Apoptotic and mitotic index, DNA index, ratio of cells in S phase, p53 protein overexpression in untreated tumours as well as the changes of these parameters after the first 2 Gy irradiation except proliferative kinetics parameters were examined in order to determine the prognostic value of these factors. The data show that inducibility of apoptosis is very low in head and neck carcinomas which correlate with the unfavourable prognosis. The decrease in mitotic index after the first 2 Gy irradiation, which occurred in 7 cases--5 of them still alive--indicates a better chance for relatively longer survival. In immunohistochemically p53 positive tumours frequently occurring aneuploidy and elevated S-phase rate were found.