Combined chemotherapy (PP therapy) using cisplatin (CDDP) and peplomycin (PEP) was performed as induction chemotherapy for 31 patients with cancer of the tongue, and the clinical and histopathological effects were investigated. As the primary clinical effect, complete response (CR) was observed in three cases, partial response (PR) in 20 cases, minor response (MR) in six cases and no change (NC) in two cases, with a clinical response rate of 74.2%. The histopathological effects of the chemotherapy in the following cases showed these histological Grades: 0 or I in four cases, IIa in 12 cases, IIb in eight cases, III in six cases and IV in one case. Fifteen of the 31 patients who received PP therapy showed a histological Grade of IIb or better, representing 48.4% of the histopathological response rate. With regard to the mode of invasion of the tumor, the histopathological response rate was 90.0% in patients with invasive Grades 1 and 2, 41.7% in those with invasive Grade 3 and 16.7% in those with invasive Grade 4C. There were no patients with invasive Grade 4D in whom the therapy was histopathologically effective. In other words, the histopathological effect significantly decreased as the invasive Grade increased. With regard to the relationship between clinical effects and histopathological effects, there was one CR patient who showed a histological Grade of IIa. Thus, it is noteworthy that clinical effects were not necessarily consistent with post-chemotherapeutic histopathological effects.