Three cases of plunging ranula are reported and the literature reviewed. Extravasation of saliva from the sublingual gland due to trauma or obstruction of its ducts appears to be the most likely cause of plunging ranula. Available data suggest that the submandibular gland is usually not involved, although at the time of surgery it may be extremely difficult to exclude a submandibular origin of the cyst in the neck. Communication between the oral and cervical components of the plunging ranula probably occur via a hiatus in the mylohyoid muscle. Such communication passing directly into the submandibular compartment may simulate submandibular gland involvement. Since 1910, 139 procedures in 89 patients with plunging ranula have been reported in the English literature. The recurrence rate was 70 per cent after incision and drainage of the cyst, 53 per cent after marsupialization, 85 per cent after excision of the cyst in the neck and 2 per cent after excision of the sublingual gland via the cervical or intra-oral route. This review suggests that excision of the sublingual gland with intra-oral drainage of the cervical swelling appears to be the treatment of choice for the plunging ranula.