This first report of a Swiss registry includes 313 patients with primary immunodeficiency syndromes (PIDS) who were observed between January 1975 and January 1985. Diagnosis of specific PIDS was made according to WHO criteria. The most frequent disorders were IgA deficiency (33%) and common variable immunodeficiency (22%), followed by selective deficiency of other immunoglobulin isotypes (9%), severe combined immunodeficiency (9%), infantile sex-linked agammaglobulinemia (7%), and Wiskott-Aldrich syndrome (6%). Frequencies of other types of PIDS varied between 0.3 and 4%. Half of the patients were in the pediatric age group. Male patients predominated (63%). In addition to respiratory and urogenital tract infections, autoimmune disorders were observed in 14 patients with IgA deficiency or common variable immunodeficiency. IgA deficiency was, furthermore, associated with atopic and neurological disorders. A comparison with other national registries revealed some differences: the frequency of severe combined immunodeficiency was high (incidence, 24.3 cases per 10(6) live births), and that of ataxia teleangiectasia was particularly low (1.4 per 10(6) live births) in Switzerland. Frequencies of the three major PIDS groups of (i) predominantly antibody defects, (ii) predominantly cell-mediated defects, and (iii) PIDS associated with other major defects agreed with those reported in the other European studies.