Introduction: Generalized gingival enlargement is a rare condition of varying etiology, resulting in oral hygiene impairment and increased risk of periodontitis. Case report: A 40-year old male was presented with generalized hyperplasia of the gingiva, halitosis, bleeding gums, masticatory difficulties and compromised aesthetic. While the medical history was unremarkable, a positive family history was reported, since his mother was also affected. Clinical examination showed a firm, dense generalized gingival overgrowth, massive plaque, subgingival and supragingival calculus, and tooth migration. Periodontal charting revealed active deep pseudo pockets and periodontal pockets. Generalized bone resorption was radiographically detected. Histological examination revealed connective tissue with dense collagenous fibers, large numbers of fibroblasts, fibrocytes and high quantity of chronic inflammatory cells. A hereditary gingival fibromatosis (HGF) and severe chronic periodontitis were diagnosed. Initial periodontal therapy with adjunctive systemic antibiotics was followed by surgical excision by means of internal gingivectomy and open flap debridement. Significant clinical improvement was achieved and remained stable up to one year. In addition, orthodontic treatment and periodontal maintenance are recommended. Discussion: Gingival fibromatosis can be caused by number of factors, e.g. by inflammation, leukemic infiltration, systemic medication, or genetic origin is considered (hereditary isolated or as part of a syndrome). An association of HGF with periodontitis requires a combined antiinfective and surgical treatment approach. Conclusion: HGF should be managed as early as possible to prevent periodontitis and further functional and esthetical impairment. Regular supportive periodontal therapy is important to maintain the treatment success. Keywords: gingival overgrowth, hereditary gingival fibromatosis, internal gingivectomy