Fifteen patients with malignant tumors were entered into an early phase II study of hypoxic cell radiosensitive RK28 during Nov. 1989 to Mar. 1991. The treatment regimen consisted of a 0.4g/m^2 IV, I A infusion twice a week or LI(local injection). Fourteen patients were evaluable for response. Six partial responses were observed. The main adverse effect was nausea/vomiting (53%). The results of animal experiments in RK28 I A infusion on rabbit VX2 tumor system were also demonstrated.