Actinomyces spp. are located without displaying any pathogenic effect in the oral flora. However, the disruption of oral microenvironmental balance, mucosal tissue integrity, and defense system can cause microorganisms to settle on deep periodontal tissues and to induce pathologic reactions. The present case report describes erythematous and desquamative lesions with pseudomembrane limited to the gingiva. In the histopathologic examination, Actinomyces colonies were isolated from the gingiva. On the basis of histopathologic and laboratory findings, the lesions were diagnosed as Actinomyces-associated lesions of the gingiva. No condition that caused immuno suppression was present in the patient. Nevertheless, local effect of the chlorhexidine mouthwash usage for a period may induce irritation of the oral keratinized tissue. The localized form of actinomycotic lesions occurs seldom in the gingival tissues. In rare cases like this, the practice of differential diagnosis with a multi-disciplinary approach is very important for the accurate diagnosis and appropriate treatment planning.