Mandibular fractures in infants are rare. This case report describes management of a mandibular fracture in an 11-month-old infant using a microplate and screws with open reduction. The surgical treatment was successful. Because the bone fragments were displaced and only the primary incisors had erupted, conservative treatment, such as an acrylic splint and circummandibular wiring, was not recommended. Nine weeks after surgery, the microplate was removed. The results showed complete clinical and radiological bone healing with normal eruption of deciduous teeth.