Severe congenital neutropenia (SCN) comprises a heterogenous group of disorders characterized by a constantly low absolute neutrophil count (ANC) below 0.5 × 109/l in the peripheral blood and maturation arrest of the myelopoiesis in the bone marrow at the promyelocyte/myelocyte stage that lead to early onset of severe bacterial infections in affected patients. Clinical symptoms of congenital neutropenia include sepsis, recurrent respiratory tract infections, mouth ulceration, chronic gingivitis, bacterial skin infections, and urinary tract infections. Patients with SCN often develop periodontitis despite standard medical and dental care. We present oral symptoms in our patient afflicted with SCN due to homozygous mutations in the JAGN1 gene, based on 16 years of observation and treatment at the Paediatric Dentistry Clinic of Children's Memorial Health Institute. In our patient, oral cavity changes typical for SCN - in the form of gingivitis and bleeding from periodontal tissues - appeared around the age of 2 and led to the premature loss of primary teeth. The patient also developed an advanced periodontal disease in the permanent dentition, resulting in the loss of 21 teeth at 15 years of age. Dental care of patients with SCN should be carried out in close cooperation with an immunologist, and dental procedures associated with the risk of bacteremia require antibiotic prophylaxis.