Kostmann disease is a rare born-with disorder seen as extreme neutropenia due to abnormally low myeloid differentiation in the bone marrow, with the neutrophil count being less than 500_103 cells/l. Male child 4.5-year old complains from a bilateral aural discharge of 2 years duration. By examination, there is a gapped post auricular wound with necrosis in parts and inflamed lower part of the mastoid and upper part of the neck, and bilateral central tympanic membrane perforation with pulsating discharge. Hematological investigations were done that reveal severe neutropenia (Kossmann disease). Canal wall down (CWD) mastoidectomy with wide meatoconchoplasty for exteriorization of the cavity was done. Removal of infected tissues in the postauricular region, the undermining of skin and primary repair was done in two layers. After that, ear discharge and postauricular swelling improved and patient with good general condition with an excellent outcome. So, a mastoid abscess can be a presenting complaint of Kostmann disease.