From experimental observations, Peplomycin was expected to be more active against a variety of tumors and to be less toxic for the lung than the parent compound. An intermittent dose(10mg. twice a week) of peplomycin was tested in patients with malignant lymphoma or squamous cell carcinoma who had failed conventional treatment. There were two cases of CR and five cases of PR in twelve cases with malignant lymphoma, and two cases of PR in fourteen cases with squamous cell carcinoma. Out of 26 cases treated with peplomycin, fever was seen in ten cases(38.5%) and pulmonary complication was seen in five cases (19.2%). These data obtained from peplomycin treatment were compared with the results obtained from our previous experiences with bleomycin. Response rate, spectrum and frequency of side reactions of peplomycin treatment were substantially identical with those of bleomycin treatment. However, remission duration and life span were much longer in peplomycin treatment. In this respect, peplomycin seems to be superior than bleomycin to a certain extent.