The immune system is a network of interconnected components that promote the protection against pathogens and cancer, in addition to ensuring the homeostasis between cells of the various organs and systems of an individual. Immunodeficiencies are defects in one or more components of this system, which are sometimes lethal. The immunodeficiencies are divided into two branches: primary, also known as congenital, and secondary, resulting from disturbances in other systems indirectly affecting the immune system. Among the primary, there are either defects in the innate (or natural) immune response, such as disturbances in phagocytes and the complement system, or in the adaptive branch, such as defects in the production of antibodies (or immunoglobulins), also known as humoral immunodeficiencies, and those related to disturbances in T cells (cellular immunodeficiencies), such as the severe combined immunodeficiencies (SCIDs). This article deals with the most common primary immunodeficiencies related to events in the respiratory tract, namely the common variable immunodeficiency (CVID), the IgA deficiency and chronic granulomatous disease (CGD). This paper also addressed the clinical, laboratory and treatment of primary immunodeficiencies (PIDs) in order to increase awareness of these diseases in many aspects that are not known in its depth.