Immunological assessment was carried out in 67 patients with various stages and histological grades of squamous cell carcinoma of the uterine cervix and compared with normal controls to discover whether any of these parameters could be used as an indicator of the patient's clinical status. The results show a gross impairment of the various lymphocyte subpopulations and anti-tumor immunity. This impairment was more pronounced in patients with high tumor load and having a histology of poorly differentiated squamous cell carcinomas. None of the parameters studied (total leukocyte numbers, lymphocyte subpopulations, leukocyte adherence inhibition test, natural killer cell activity, circulating immune complexes, and blocking effect of autologous serum) could be used as a clinical indicator, since no correlation could be noted between immune impairment and either the lymphocyte subpopulations or the circulating immune complexes.