Aims - To review the results of long term high dose intravenous immunoglobulin treatment. Methods - 162 treatment years in 18 patients with hypogammaglobulinaemia who received intravenous immunoglobulin treatment between 1973 and 1993 were reviewed. Results - A mean dose of 0.42 g/kg immunoglobulin resulted in a mean trough IgG concentration on the 23.5th centile for age. The subjects enjoyed a good standard of health. Infection rates were similar to the general paediatric population and a similar pattern of infections occurred. There were only 0.06 episodes of pneumonia and 0.11 hospital admissions per year of treatment. The development of chronic pulmonary disease was significantly related to trough IgG concentrations less than the 10th centile (p < 0.009), however, this developed in only two children after the start of treatment. All children had normal growth parameters. Adverse reactions to immunoglobulin infusions reduced from 9.1% to 0.8% after the introduction of low pH modified intravenous immunoglobulin in 1986. Although minor, transient increases in liver transaminase values were common; none of the 11 patients tested by hepatitis C polymerase chain reaction were positive. Conclusion - Children with hypogammaglobulinaemia who are receiving replacement treatment grow normally and have an infection rate similar to that of nonimmunodeficient children. No evidence of transmission of hepatitis C virus by the Commonwealth Serum Laboratories immunoglobulin was found.