It is now more than a decade since the door was thrown open to medical treatment of hairy cell leukemia (HCL). Five out of 6 patients with the disease had responded to leukocyte interferon (α-IFNleu). And throughout the years following, all new drugs developed for low-grade non-Hodgkin’s lymphomas (NHL) triggered excellent activity in this rare leukemia. The review describes the potential, dosage, and handling of the 3 new antileukemic drugs in HCL that emerged after the detection of the efficiency of the human natural α-IFN]eu with its limited supply: the technically producible recombinant IFNs alpha-2a-c (rhIFN), deoxycoformycin (DCF), and 2-chlordeoxyadenosine (2-CdA). It then proceeds to familiarize the physician with the therapeutic use of the new nucleoside analogues and to recall the efficacy of IFN. The main sources of information are the reports which described the results of studies and investigations before approval in the USA and several nationwide trials from Europe. All in all, the antileukemic potential of the 3 drugs in treatment of HCL is nearly identical, extinguishing all other known prognostic factors. However, some patients still need individual approaches to problems which have evoled throughout the course of the disease. It then touches on the use of the growth factors, colony stimulating factors (CSF), in patients with severe neutropenia or active infections. Finally it reminds the reader that although the antileukemic effect of all 3 drugs seems practically guaranteed, he has a physician may be able to improve their benefit by a strictly problemoriented approach. Some patients ought to have preparative support, selected medication, a sequence or a combination of drugs.