Gingival enlargement, an abnormal growth of the periodontal tissue, is mainly associated with dental plaque-related inflammation and drug therapy. Its true incidence in the general population is unknown. Gingival enlargement produces aesthetic changes, pain, gingival bleeding and periodontal disorders. Although gingival overgrowth has been traditionally recognised as an adverse effect of phenytoin therapy, it has recently been reported in association with the use of cyclosporin and calcium antagonists. These 3 classes of drugs produce important changes in fibroblast function, which induce an increase in the extracellular matrix of the gingival connective tissue. In the majority of those patients for whom dosage reduction, or drug discontinuation or substitution is not possible, and for whom prophylactic measures have failed, surgical excision of gingival tissue remains the only treatment of choice.