Dear Editor, Dermoid cysts of the floor of mouth are quite uncommon, and only 1.6% of dermoid cysts are located in the floor of the mouth. 1 These cysts are classified into two types by location as follows: sublingual type is located between the oral mucosa and geniohyoid muscle and submental type arises between geniohyoid muscle and the skin. These cysts are distinguished into two groups as follows: one is the midline type, the other is the lateral type. 2 Various surgical techniques were reported for excision of the dermoid cysts of the floor of the mouth; midline vertical, bilateral incision along the mandibular crest, midline glossotomy, modified midline glossotomy and transcutaneus approaches. 3 This paper describes a technique that ensures success for enucleating large median geniohyoid dermoid cysts of the floor of the mouth which do not need an extraoral or transcutaneous route (Fig. 1). This technique has been used by the senior author in a case series of three patients over a period of 2 years, and one of them was reported in a previous case report as having a large dermoid cyst of the floor of the mouth. 4 Surgical steps1. The operation is performed under general anaesthesia with nasal entubation. 2. Braun cannulas are placed before incision to prevent Wharton duct injury. 3. Dingman retractor is placed and local anaesthetic is injected into the sublingual space. 4. The incision is done as inferior based U-shaped -reverse U -and then a thin mucosal flap is elevated over the cyst wall superiorly and bilateral laterally. (Fig. 2) 5. While dissecting the cyst with meticulous blunt dissection, the borders of the cyst are also determined. 6. After determining the borders of the cyst, aspiration and a small incision to the thick fibrous wall of the Fig. 2. U shaped flap elevation and aspiration of the cyst content to decrease the size.