Two thousand and fifty cases (n = 2050) of primary immunodeficiencies (PID) were registered up to February 2001. The Spanish Register for Primary Immunodeficiencies (REDIP) began in 1993. PID nomenclature and diagnostic criteria were made according to the report of the World Health Organization Scientific Group (1999). The most frequent disorders were IgA deficiency (797 registers) and common variable immunodeficiency (CVI) (389), followed by severe combined immunodeficiency and predominantly T cell defects (268), complement deficiencies (207 registers), X-linked agammaglobulinemia (87), IgG subclass deficiency (71), chronic granulomatous disease (64). Gammaglobulin replacement was the therapy in 638 patients (76%) belonging to antibody deficient group. 61 bone marrow transplants were done, 46 severe combined immunodeficiencies, 6 phagocytic disorders and 1 unclassified. Important differences in the number of cases submitted from different country areas were found.