Cyclic Neutropenia (CN) is characterized by recurrent infections, fever, oral ulcerations, and severe periodontitis as result of the reduced host defences. The previous studies have established the effectiveness of recombinant granulocyte colony-stimulating factor (GCSF) to increase the number and the function of neutrophils in the peripheral blood in this disease. In a 20-year-old Caucasian female with a diagnosis of cyclic neutropenia, oral clinical examination revealed multiple painful ulcerations of the oral mucosa, poor oral hygiene conditions, marginal gingivitis, and moderate periodontitis. The patient received a treatment with G-CSF (Pegfilgrastim, 6 mg/month) in order to improve her immunological status. Once a month nonsurgical periodontal treatment was carefully performed when absolute neutrophil count (ANC) was >/=500/muL. The treatment with G-CSF resulted in a rapid increase of circulating neutrophils that, despite its short duration, leaded to a reduction in infection related events and the resolution of the multiple oral ulcerations. The disappearance of oral pain allowed an efficacy nonsurgical treatment and a normal tooth brushing that determined a reduction of probing depth (PD </= 4 mm) and an improvement of the oral hygiene conditions recorded at 6-month follow-up.