Idiopathic or hereditary gingival fibromatosis is a benign oral disorder characterized by enlargement of the oral gingival tissues. This article describes a case of a female child who exhibited a generalized gingival overgrowth in both arches at birth. Other causes of gingival overgrowth and the clinical, radiographic, and histopathologic characteristics are discussed. Treatment consisted of surgical removal of the hyperplastic fibrous tissue in a series of gingivectomies. Medical history, clinical examination, and histopathologic and genetic findings were essential to rule out other systemic abnormalities. This unusual case of nonsyndromic idiopathic gingival fibromatosis was followed for 5 years, and no recurrence was seen. Keywords: gingival overgrowth, idiopathic gingival fibromatosis, surgical treatment