A phase II trial of which preliminary results are available for 22 patients indicates that aclacinomycin applied in a continuous modality induced complete and partial remission in four of nine patients with acute lymphoid leukaemia that was resistant to all previously available drugs, and in four of eight patients with stage V lymphosarcoma (leukaemic). Bone-marrow toxicity was the major side-effect. Only one patient of 20 suffered from cardiac toxicity; no one had alopoecia. This very low incidence of myocardial lesions and the absence of hair loss had been predicted, respectively, by our electron microscope study of the myocardium and the light electron microscope study of the skin of golden hamsters [7], a test that detects frequent severe myocardium and skin toxicities for adriamycin and some anthracyclin analogues such as detorubicin, which was found to be toxic in a high percentage of patients in a clinical trial conducted by the E.O.R.T.C. Clinical Screening Group [8].