The X-linked agammaglobulinemia (XLA) is a rare immunodeficiency, characterized by absence or accentuated diminuition of all the isotypes of serum immunoglobulins and greater susceptibility to infections, mainly after the sixth mouth of life. The authors present nine patients bearers of XLA, with recurrent infectious processes (pneumonias 7/9, otitis 7/9, sinusitis 5/9, sepsis 5/9, diarrheas 3/9, infectious arthritis 3/9, meningitis 3/9, pyodermitis 3/9, viral encephalitis 1/9), with the beginning of symptoms on average in a nine months life. The laboratory examination showed absence of antibody response, with normal cellular immunity. The patients received immunoglobulin with control of the infectious processes. Five children received prophylactic antibiotic therapy for sinusitis control. The precocious diagnosis of XLA is of extreme importance, with institution of therapy with intravenous immunoglobulin for reduction in infectious process occurrence and complications, besides improving the patient's life quality.