4-Demethoxydaunorubicin (4-DMDR) was administered orally at the dose of 15 mg/m2 daily for 3 consecutive days at three-weekly intervals to 28 patients with advanced pretreated breast cancer and 9 patients with disseminated pretreated melanoma. A partial remission was observed in 6 out of 20 evaluable breast cancer patients (30%) for a median duration of 6 months and in one out of 7 evaluable patients with melanoma (14%) for a duration of 3 months. Side-effects included leucopenia in 78% of patients (less than 1000 wbc/cmm in 8%), nausea in 32% and mild vomiting in 16%. The preliminary results of this ongoing study on 4-DMDR administered orally show that the regimen is well tolerated in the majority of patients and that it has antitumour activity in advanced breast cancer.