Hereditary gingival fibromatosis (HGF) is a rare gingival lesion that presents as localized or generalized enlargement of the attached gingiva. It usually develops as an isolated disorder but can be one feature of several multi-system syndromes. Gingival hyperplasia may induce diastema, malocclusion and prolonged retention of primary teeth. Severe hyperplasia gingiva can cover the crown of the teeth, which cause appearance and functional impairment. This presentation reports four severe gingival hyperplasia cases. Three cases are members of a family. The fourth case belongs to the other HGF family. Three adult cases received gingivectomy. Qsteoma formation was noted under the overgrowth gingiva during surgeries. After surgery, the esthetics of these patients improves. The treatment of another adolescent patient was scaling and oral hygiene instruction. Because the 12 year-old patient is during puberty, the surgical excision was deferred and we choose conservative treatment for the patient.