Recurrent respiratory tract infections are one of the most common manifestations of primary immunodeficiencies in children. The diagnosis is often based on the results of broad differential diagnostic procedures. These should include not only evaluation of the immune system and identification of the infectious agents, but also clinical evaluation which should take into consideration variable manifestations from different organs and systems which together comprise the syndrome. The aim of this study is to present both the pathogenetic aspects of Nijmegen breakage syndrome, with particular emphasis on immunodeficiency and clinical manifestations and also of difficulties accompanying diagnostic procedures. The material of the paper consists of a presentation of the case of a nine-year old girl with Nijmegen breakage syndrome, manifesting symptoms of advanced respiratory disease. Diagnosis of the primary immunodeficiency syndrome requires the standards used in diagnosis and therapy of the immune system.