Idarubicin is the first anthracycline that can be administered orally facilitating antineoplastic chemotherapy at an improved quality of life. In different studies idarubicin has proved clinical effectiveness in patients with advanced low grade non Hodgkin's lymphoma. We performed a phase II study in 19 patients with untreated and pretreated B-CLL of Binet stage A-C. Idarubucin was administered orally at a dose of 15 mg/m2 over 3 days every 4 weeks. Of 19 evaluable patients (m:f, 16:3, median age 64 years, range 41-80 years) 7 were previously untreated while 12 patients had received prior therapy with fludarabine, chlorambucil or similar non-anthracycline containing regimens. 12 pts had Binet stage C, 5 Binet stage B and 2 Binet stage A. Five patients achieved a partial remission (26%), 5 patients had stable disease (26%) and 9 patients showed progressive disease (47%), resulting in an overall response of 26% (5/19). There was no correlation of response rate with Binet stages or previous treatment regimens. Treatment associated side effects consisted predominantly of mild nausea and vomiting (26%) as well as minor infections (21%) and diarrhoea (16%). These data demonstrate that oral idarubicin as a single agent is well tolerated but of limited effectiveness in B-CLL. Further studies are needed to assess different doses and schedules of oral idarubucin and to test it in combination with other chemotherapeutic agents.