Abstract: We studied the therapeutic effects of intratumor injection of DNCB solution in mouse transplanted Ehrlich tumor and investigated the mechanisms of antitumor activity. The results showed that multiple intratumor injection of DNCB solution could destroy established subcutaneous Ehrlich solid tumor in Kunming mice. Mice in treated group survived much longer than those in control groups by rejecting thd tumor mass and obtained the specific immunity by resisting the rechallenge of the same tumor cells.Pathological studies demonstrated that, with presensitization to DNCB,a single intratumor injection of DNCB solution produced massive tumor tissue necrosis directly, followed by lymphocyes infiltrating at the tumor site, espcially at the edge of tumor mass, which suggests that immunological mechanisms as well as non-immunological mechanisms are responsible for the antitumor activity.