Gingival enlargement is common among patients and can be caused by a variety of etiological factors. The most common reason is poor oral hygiene and high bacterial load that leads to gingival inflammation and enlargement. Other implicated factors include systemic drugs, such as Phenytoin (Dilantin) taken by epileptic patients, Calcium Channel Blockers such as Nifedipine (Procardia) and Verapamil (Calan) for the treatment of hypertension, arrhythmia and angina. Another class of medication associated with gingival enlargement is immunosuppressive agents given to organ-transplant patients to prevent rejection of the new element, such as Cyclosporine. Some enlargements could be associated with other conditions such as puberty, pregnancy or diabetes or be a symptom of a systemic disease (leukemia, Wegener's granulomatosis or sarcoidosis). In rare cases the cause for the enlargement is genetic and termed Hereditary Gingival Fibromatosis (HGF). HGF is a genetic disorder characterized by a progressive enlargement of the gingiva. Histologically, the gingiva is characterized by an accumulation of dense fibrous connective tissue. This is believed to be due to an imbalance between synthesis and degradation of extracellular matrix composed mainly of collagen molecules or due to an alteration in fibroblast proliferation. Different pathogenic mechanisms have been proposed and examined over the years but no precise process has been identified. The main objective of this paper is to discuss this genetic anomaly and support it with clinical cases of a mother and her two children. It will focus on the clinical and histologic characteristics of HGF as well as known biologic and genetic features and treatment modalities.