Darier's disease, also known as keratosis follicularis or dyskeratosis follicularis, is a rare disorder of keratinization. It is an autosomal dominant genodermatosis with high penetrance and variable expressivity. Its manifestation appears as hyperkeratotic papules primarily affecting seborrheic areas on the head, neck, thorax, and less frequently the oral mucosa. When oral manifestations are present, the palatal and alveolar mucosae are primarily affected. They usually asymptomatic and are discovered in routine dental examination. Histologically, the lesions present as suprabasal clefts in the epithelium with acantholytic and dyskeratotic cells represented by "corps ronds and grains." This paper reports a case of an adult male patient who presented with painful whitish lesions on buccal mucosa with crusty lips as the only clinical sign of Darier's disease. As this patient did not have skin lesions or family history, an intraoral biopsy confirmed the diagnosis of Darier's disease by a multidisciplinary team.