Five consecutive patients with progressive extracutaneous stage IV mycosis fungoides (MF) were treated with VM 25, 100 mg/m2 i.v., for at least 3 cycles. All patients had been extensively pretreated and in particular with vinca alkaloids. Two partial responses of 5 and 9+ months duration and 1 minimal response of 5 months duration were obtained. Transient myelosuppression was encountered in all patients. These preliminary results should encourage further exploration of VM 26, even in less advanced MF.