Seven patients with B-cell leukaemia - six with chronic lymphocytic leukaemia (CLL) and one with B-prolymphocytic leukaemia (B-PLL) - were treated with CAMPATH-1H*, a genetically reshaped CD52 monoclonal antibody, administered subcutaneously (s.c.) three times a week for 6-12 weeks. Four were resistant to, and three had had a short partial remission (PR) following, nudarabine chemotherapy. The patient with B-PLL achieved complete remission and three patients with CLL attained PR; two of the latter were retreated, The three remaining patients were non-responders. Three patients were transfusion-dependent before CAMPATH and all three became transfusion-independent after treatment. The overall median survival from starting CAMPATH-1H was 11 months, Three patients reactivated cytomegalovirus (CMV) during the course of treatment, and two were treated with, and responded to, ganciclovir.