The incidence of plunging ranula has been reported as about 10% of all ranula cases. Treatment consists of wide surgical excision or marsupialization. However, it seldom provides a satisfactory result and various modalities of treatment have been proposed in addition to surgical extirpation. We reported our experience using intralesional OK-432 sclerotherapy for a case of plunging ranula in 20 year-old male patient. The OK-432 solution was prepared by dissolving 0.1 KE in 2ml of physiologic saline and was instilled in the same amount of the aspirated cystic fluid. Following two instillations, the lesion completely disappeared. The side effects were mild fever for 3 days and a mild local induration for several days. At present, 9 months after instillation, no recurrence was observed. OK-432 sclerotherapy appears to be simple, safe and effective method for the treatment of plunging ranula.