Primary immunodeficiencies are rare immunologic diseases whose main characteristics are recurrent infections. These diseases are frequently unsuspected and the delayed diagnosis makes complications irreversible with the consequent poor quality of life. In Mexico, primary immunodeficiencies have a low prevalence, which is secondary to under-diagnosis and the lack of specialized laboratory studies in most hospitals. Since there is a registration of primary immunodeficiency cases in Europe and other developed countries, it is possible to estimate the incidence of primary immunodeficiencies and to elaborate guidelines of diagnosis and treatment. In our country we do not have any epidemiological registry; however, from 1998 to 2004 the number of cases of primary immunodeficiency has increased; the minimal incidence calculated is 0.16 to 0.24 per 100,000 births for chronic granulomatous disease, severe combined immunodeficiency and X linked agammaglobulinemia, this data is still very low compared to other international registries. We present an epidemiological review of primary immunodeficiency prevalence in Mexico compared to some international reports.