Intramuscular and intravenous gammaglobulin treatment for hypogammaglobulinaemia is often associated with systemic adverse reactions in some patients. Subcutaneous infusions of gammaglobulin are usually given at a slow rate. To assess the safety of home treatment with subcutaneous gammaglobulin, rapid infusions (34-40 ml/h) given by small portable pumps were used to treat twenty-five patients with hypogammaglobulinaemia. Fifteen patients had previously had adverse reactions to intramuscular or intravenous gammaglobulin treatment. After the patients had been taught how to use the pumps during 6 months of treatment in hospital, in which they initially received 100 mg of an intramuscular gammaglobulin preparation/kg per week, they went on to use the pumps at home or at work. So far, the patients have given themselves 3232 rapid subcutaneous infusions (2308 in home therapy). A median pre-infusion serum IgG concentration of 8.1 g/l resulted after 6 months of treatment. There were only 30 (0.93%) mild systemic adverse reactions; there were fewer reactions with subcutaneous gammaglobulin than with previously given intramuscular injections (n = 21, p less than 0.001) or intravenous infusions (n = 9, p less than 0.001) in this group of patients. Overall, the patients spent 0.2 days a year in hospital due to respiratory tract infections. The findings show that the method for subcutaneous administration is very easy to learn and is appreciated by the patients; moreover, the infusions can be given much faster than previously reported without any pronounced local reaction.