The incidence ranging of the dermoid and epidermoid cysts on the head and neck, from 1.6 to 7.0%, and they represent less than 0.01% of all oral cavity cysts. Histologically, they can be further classified as epidermoid, dermoid or teratoid. We analyzed two rare cases of large epidermoid cysts of the floor of the mouth, with sublingual as well as submental component resembling plunging ranula. Two female patients (age 15 and 16 y. o.), who’s had sublingual and submental swellings of oral floor with breathing and swallowing difficulties. The suspected clinical diagnosis of the sublingual dermoid or epidermoid cysts were supported by the radiological finding after performing ultrasonography (USG), computed tomography (CT) and magnetic resonance imaging (MRI). On the radiological investigation the differentiation between epidermoid cysts, ranulas, cystic tumours, mucous extravasation phenomena and hygromas sometimes indistinguishable, leading in the determination of internal component differentiation and has pathognomonic signs to differentiate. The lesions were surgically excised using an intraoral approach. Microscopic examinations revealed a dermoid cyst of the epidermoid type. Keywords: Sublingual Epidermoid Cyst, Plunging Ranula, Ultrasonography, Computed Tomography, Magnetic Resonance Imaging