A case of a 22-year-old male with 5 recurrent pneumonias was recently encountered, resulting in an extremely low immunoglobulin level and a diagnosis of X-linked gammaglobulinemia. This disease is an immunodeficiency disease, the first case of which was seen in 1952 and is called Bruton’s disease. It most often starts after 4 to 6 months of age and presents with recurrent infections with extracellular bacteria such as Streptococcus pneumoniae, Streptococcus haemolyticus and Haemophilus. The most common ones are sinusitis, pneumonia, otitis media, boils, meningitis and sepsis. Serum IgG is constantly below 2 g/L; IgA and IgM levels are both extremely low or difficult to measure. The genetic defect in this disorder is on the long arm of the X chromosome (Xq21.3-22). Early initiation of gammaglobulin (C globulin) replacement therapy can prevent systemic infections, improve prognosis, and lead a normal human life. In most cases, gammaglobulin is administered at a dose of 0.35-0.5g/kg per month or 0.15-0.25g/kg every 2 weeks, and serum IgG is maintained at 3-4g/L.