Plasma cell gingivitis is a benign lesion of unknown etiology characterized by massive infiltration of plasma cells into the connective tissue of the gingiva. Clinically it presents as a gingival enlargement with erythema and some areas with the presence of desquamation, it is usually asymptomatic, but on some occasions the patient may present pain and gingival bleeding. Diagnosis requires clinical-pathological correlation. Based on the foregoing, we present a case report of a 25-year-old female patient diagnosed with plasma cell gingivitis with idiopathic etiology based on the clinical and histopathological study.