X-linked agammaglobulinaemia (XLA) is a rare immunodeficiency disorder affecting only male subjects. There is an absence of all serum immunoglobulins and circulating B cells. T-cell function and numbers are normal. The clinical characteristics are recurrent pyogenic infections starting in infancy, hypoplasia of lymphoid tissue and a family history in about half the cases. Ten patients with XLA have been seen over the last 14 years at Red Cross War Memorial Children's Hospital, Cape Town. Chronic infections causing significant morbidity occurred in half our patients and 2 have died. Intravenous of gammaglobulin replacement therapy is superior to the intramuscular form. The recommended dose is 200-400 mg/kg/mo., although the optimal dose and frequency of the gammaglobulin infusion should be individualised for each patient.