Drug-induced gingival overgrowth remains the most widespread unwanted effect of systemic medication on the periodontal tissues. Gingival enlargement represents an over-exuberant response to a variety of local and systemic conditions. Gingival enlargement produces aesthetic changes and clinical symptoms including pain, bleeding, speech disturbances, abnormal tooth movement, occlusion problems, problems in mastication, enhancement of caries development and periodontal problems. The medication-induced gingival overgrowths occur as a side effect following administration of drugs used mainly for non-dental treatment and thus the overgrowth cannot be explained as a variation of the intended pharmacological action of the drug. Currently, more than 20 prescription medications are associated with gingival enlargement. This book is an insight addressing this issue in detail.