Summary: Congenital immune deficiencies (CID) are a group of heterogeneous genetically determined disorders that predispose individuals to an increased risk of infection, especially atypical and severe infections. To date, 508 different mutations leading to various CID phenotypes have been identified. The most common immune deficiency in the population is IgA deficiency. Primary immunodeficiencies (PID) can affect both non-specific (innate) and specific (acquired) response mechanisms. Upper respiratory tract infections are often the first manifestation of PID. There are six symptoms indicating an increased risk of WBO, and the presence of two of them is sufficient to suspect WBO in a patient (according to the European Society for Immunodeficiencies). First, secondary causes should be ruled out, and only then should tests aimed at diagnosing PID be ordered. It is important to collect a detailed medical history and perform a physical examination, as we can expect to find specific abnormalities. In the next stages, screening laboratory tests are performed, followed by more in-depth tests. First, a complete blood count with smear, proteinogram, and determination of IgA, IgM, IgG, and IgE antibody levels should be performed. If abnormalities are found, the patient should be referred to a clinical immunologist or pulmonologist with experience in this pathology for a definitive diagnosis. Early diagnosis and treatment of patients with CIDN not only significantly improves their quality of life by reducing the frequency of infections, but also limits the occurrence of complications in the natural progression of the pathology.