Intravenous immunoglobulin replacement therapy reduces the number of bacterial infections in B-cell chronic lymphocytic leukaemia (B-CLL) patients. However, due to the complexity of immunodeficiency in B-CLL and the cost-effectiveness of replacement therapy, it is important to identify patients who are likely to benefit from the treatment and to investigate which dose should be used. 15 patients with hypogammaglobulinaemia and a history of recurrent infections received a fixed dose of 10 grams of gammaglobulin intravenously every 3 weeks. Serum IgG levels were significantly higher after three doses (p = 0.0002), and stabilized just above lower reference value after 11 doses. The total number of infection-related events during 168 months before therapy was compared to the total number of infection-related events in 169 months during therapy. The number of antibiotic prescriptions was reduced from 78 to 54 (N.S.), the number of admissions to hospital due to infections was reduced from 16 to 5 (p = 0.047) and the number of febrile episodes was reduced from 63 to 31 (p = 0.004). We conclude that a fixed low dose of gammaglobulin intravenously can restore normal serum IgG levels in hypogammaglobulinaemic B-CLL patients, and leads to a decreased number of febrile episodes and admissions to hospital due infections.