Although surgery is the first choice of therapy for plunging ranula, it is associated with technical difficulties, morbidity and recurrence. Plunging ranula may be also primarily treated with nonsurgical sclerotherapy, but there is little experience in pediatric patients. We, therefore, assessed the efficacy of OK-432 sclerotherapy for pediatric plunging ranula. Nine children with plunging ranula were prospectively treated with intracystic injections of OK-432. At the outpatient clinic, the ranula was punctured in the neck and aspirated mucus was replaced with 0.1-0.2mg OK-432 solution. The size of the ranula was compared before and after sclerotherapy. Total or nearly total shrinkage was observed in 6 of 9 patients; marked reduction (>50% of original size) in 2; and partial reduction (<50% of original size) in 1. At a mean follow-up of 26 months after last sclerotherapy, recurrence was observed in only 1 patient; this patient showed complete response after reinjection of OK-432 solution. No significant complications were observed, with only fever and mild local pain observed in 4 patients for 2-4 days after treatment. OK-432 sclerotherapy is safe and effective in the treatment of pediatric plunging ranula. Sclerotherapy may become a primary treatment modality prior to surgery.