Malignant acanthosis nigricans is a paraneoplastic cutaneous syndrome. Clinical findings such as tripe palms and mucocutaneous papillomatosis in atypical sites such as the oral mucosa are strong indicators of a visceral malignancy. We report on a rare case of oral acanthosis nigricans who presented with a 2.5-month history of diffuse hyperkeratotic verrucous papillomatous lesions in the entire oral mucosa which were symptomatic only when eating. Based on the clinical and histopathological findings, acanthosis nigricans with serous type endometrial carcinoma was diagnosed. However; the patient defaulted follow-up after the diagnosis and she died two months later.