Efficacy of a combination therapy, using IFN-β (Feron ®) and chemotherapy (mainly DAV), has been investigated for each stage of malignant melanoma at 65 institutions throughout Japan. This is a tentative report of this nation-wide investigation. The above combination therapy was administered prior to surgery, and after surgery, for 4 or more cycles in Stage I and II patients, 6 or more cycles in Stage III, and as many cycles as possible in Stage IV. To dete, survival rates are 100% in Stage I patients (27/27) and 48.6% in Stage IV (4/9) . These survival rates are higher than previously reported findings regardless of. the patients previous treatment. In addition, in both new and existing cases, survival rates in Stage II (55 cases) and III (82 cases) have been improved when compared to past findings. Observed side effects were mostly due to chemotherapy, and symptoms attributable to IFN-β rarely occurred.