AbstractWhile plaque‐induced gingivitis is one of the most common human inflammatory diseases, several non–plaque‐induced gingival diseases are less common but often of major significance for patients. The non–plaque‐induced gingival lesions are often manifestations of systemic conditions, but they may also represent pathologic changes limited to gingival tissues. A classification is proposed, based on the etiology of the lesions and includes: Genetic/Developmental disorders; Specific infections; Inflammatory and immune conditions and lesions; Reactive processes; Neoplasms; Endocrine, Nutritional and metabolic diseases; Traumatic lesions; and Gingival pigmentation.