2'-Deoxycoformycin (DCF) is an experimental drug with specific lymphocytotoxic activity which has proved effective in the treatment of some lymphoproliferative syndromes (LPS). This paper deals with the results achieved in 6 patients with LPS, five of them with T-cell and one with B-cell malignancies, who received DCF as initial (2 cases) or salvage (4 cases) therapy. One patient with adult T-cell leukaemia-lymphoma achieved complete remission maintained for 36 months of follow-up; partial remission was attained in three others and the remaining two patients failed to respond to the treatment. Kidney toxicity was seen in three cases, and in two of them it was necessary to stop the treatment. Kidney toxicity was seen in three cases, and in two of them it was necessary to stop the treatment. Other untoward effects included nausea and vomiting (2 patients), myoclonus, dysaesthesia of the limbs and conjunctivitis arida (one case each). No haematologic or infectious complications were present in association with DCF treatment.