Sixteen patients with disseminated squamous cell carcinoma of the lung and 26 patients with adenocarcinoma of the colon and rectum were given rubidazone. Only one partial remission was observed in a previously untreated patient who had local recurrence of a rectal adenocarcinoma. The main toxic effects observed in previously treated patients consisted of leukopenia and thrombocytopenia. Also observed were anorexia, nausea, vomiting, alopecia, fever, and chills. Cardiotoxicity was observed in one patient after a total dose of 720 mg/m2 of rubidazone. It is concluded that rubidazone is a relatively inactive compound in the management of these two diseases.