We report a case of congenital ranula with frequent recurrences.The patient was a 13-day-old boy who was referred to our clinic because of swelling of the left side of the oral floor. His parents had noticed the swelling, associated with repeated disappearance and recurrence, from birth. The patient was given a diagnosis of mucocele of the oral floor and observed. A stalk-like swelling developed at 4 months of age. Because we suspected a tumor of the oral floor, excisional biopsy was carried out. The pathological diagnosis was granulation tissue. One month after the biopsy, a transparent undulating swelling developed in the left side of the oral floor. At first, the swelling spontaneously disappeared and recurred, but then persisted. We diagnosed a ranula and incised the swelling. Abundant saliva flowed out. Five months after the incision, swelling recurred. Although repeated incisions were made, swelling recurred and resulted in difficulty in eating. Extirpation of the ranula and sublingual glands was performed under general anesthesia. There has been no recurrence of the cyst or dysfunction.We should consider extirpation of the cyst and sublingual glands in infants in whom a ranula is associated with frequent recurrence and dysfunction.