Diffuse gingival enlargement is defined as an excessive growth of periodontal tissue. It can be considered a relatively common finding, as thousands of patients have been described in the literature. Patients may seek medical attention because of pain, tenderness, interference with speech and/or mastication, halitosis, or unsightly appearance, or gingival enlargement may be an unexpected finding on routine physical examination. Diffuse gingival enlargement has numerous causes, including poor dental hygiene, medications, serious systemic illnesses, genetic conditions, other specific physiologic states, or it may be idiopathic. Given the large number of possible underlying conditions, the work-up of a patient presenting with diffuse gingival enlargement may seem daunting. We present a systemic review of diffuse gingival enlargement, including an algorithm that can be used to direct the work-up of patients presenting with this condition.