In the 9th January 2017 journal club meeting, the primary immunodeficiencies (PID), which are a diverse group of hereditary diseases leading to the impaired immune response were discussed by Milad Moloudizargari. It creates high susceptibility specially to Mycobacterium infection. High susceptibility to mycobacterial infections of patients suffering from defects of phagocytosis and combined immunodeficiencies can be explained by the predominant participation of macrophages and T lymphocytes in the specific immune response. Mycobacterium tuberculosis, Bacille Calmette-Guerin, and non-tuberculosis mycobacterium (NTM) may cause a severe disease in patients with PIDs. NTM infection can lead to severe disease in individuals with a failing immune system due to a primary or secondary immunodeficiency. Mendelian susceptibility to mycobacterial disease (MSMD) is a rare primary immunodeficiency characterized by a predisposition to severe, sometimes lethal disease caused by otherwise poorly virulent NTM, as well as the vaccine strain Mycobacterium Bovis BCG.