The cellular immunity of peripheral blood was analyzed to evaluate the efficacy of OK-432 between 3 groups of patients with oromaxillary squamous cell cancer, which were composed of 14 patients in the pretreatment stage, 8 patients who were free from cancer more than one year after the last cancer therapy and had been continuously treated with OK-432, and 14 patients who had undertaken cancer therapy without OK-432 and were also free from cancer for at least one year. As parameters of cellular immunity, leucocyte counts, percent composition of T-cells, percent compositions of T-lymphocyte subsets (OKIal+, OKT3+, OKT4+, and OKT8+) and the ratio of OKT4+ and OKT8+, PPD skin test, and lymphocytic blastogenesis induced by PHA and Con-A, were examined. The results showed no significant difference between the patients treated with and without OK-432. Nor was there any significant difference between the pretreatment group and the posttreatment groups with and without OK-432 treatments in any of the examined immunologic parameters.