Summary. T-cell large granular lymphocyte leukaemia (T-LGL) is a clonal disorder of T cells associated with neutropenia and anaemia. The clinical consequences are recurrent infections and transfusion dependence. The optimum treatment for severely affected patients remains to be defined. Current therapies require long-term administration to maintain an effect. We report the reversal of severe neutropenia and/or anaemia in four patients treated with fludarabine which has been maintained since stopping treatment. The therapeutic side-effects were restricted to one episode of fever not associated with neutropenia. We conclude that fludarabine is effective in T-LGL, may be given safely despite severe neutropenia and induces durable treatment-free remissions.