Plunging ranula is occured in about 10% of all ranula cases although surgery is the first choice therapy. However, frequent recurrences of the disease due to insufficient surgery have been reported, and various therapies have been designed in addition to surgery. We here report a case on whom we conducted intralesional injection of OK-432 for recurrent plunging ranula. A 36-year-old man was admitted who had a 2-months history of swelling of right submandibular area. He had been operated for right plunging ranula twice, 7 years ago. Under fluoroscopic guidance, contents of the ranula were aspirated and OK-432 solution was injected twice with 3-week interval. Examination after 6 weeks showed that the cystic ranula seen before therapy had disappeared completely and no recurrence was encountered after 18months. Therefore the intralesional injection of OK-432 is effective method for treatment of the plunging ranula.