The combined effect of PS-K, a protein-bound polysaccharide, and radiation therapy has been studied in patients with cancer of the uterine cervix. Thirty cases (study group) were administered daily 3g. of PS-K throughout the course of radiation. Sixty cases (control group) were treated with external cobalt-60 irradiation alone. All cases were evaluated at the dose of 1,400 rads and 3,000 rads histologically and colposcopically. Histological evaluations were performed on the punch-biopsied specimen in view of Oboshi-Shimosato's classification and the rate at which the cancer cell population diminished in the tissues. Tumor sizes were measured on the photographs obtained from the colposcopic observations. These 3 parameters were recorded, summed up and evaluated. In the control group, there was found a good, 31.7%, response, 41.7% moderate response and 26.7% poor response in the phase of 3,000 rads. However, those figures were calculated to be 60.0%, 36.7% and 3.3% respectively in study group. Hence, the administration of PS-K rendered the enhancement of the irradiation effect statistical significant (p less than 0.01). Patients were classified into two groups: very responsive and less responsive groups. Transition of immunological reactivity was analyzed. Peripheral and tissue lymphocytes counts and immunological skin test were suppressed in both groups. This can be attributed to the immuno-suppression of irradiation exceeding the enhancing effect of PS-K. The LMIT (leucocyte migration inhibition test) of the very responsive group was maintained up to the completion of the treatment in contrast to the less responsive group where it was somewhat suppressed.(ABSTRACT TRUNCATED AT 250 WORDS)