Among patients with recurrent, protracted or chronic infections of the respiratory tract involving the middle ear, 18 were found to have immunodeficiencies. In 10 of the patients, deficiency of immunoglobulins belonging to the IgG, IgA and IgM classes was found. Seven patients had an isolated IgA deficiency. One patient had a combined immunodeficiency with defects of the T-cell system and the B-cell system. One patient had an isolated T-cell deficiency.