A case of bilateral 4th brachymetatarsia treated by callotasis is reported. A 14-year-old girl visited our department because her bilateral 4th toes were naturally short and hypoplastic. X-ray showed that bilateral 4th metatarsals were as short as 15 mm. Because of cosmetic problems, she required corrective surgery. The middle parts of the bilateral 4th metatarsal were explored and small external fixation devices for distraction were applied. Osteotomy was performed while preserving the periosteum. Distraction of 0.25 mm per day commenced at 3.5 weeks after surgery. As good callus formation was recognized on serial X-rays, the value of lengthening was increased up to 0.5 mm per day at 10 weeks after surgery. Distraction was discontinued when the 4th metatarsals appeared long enough. The external device was removed at 14 weeks after surgery. No complications occurred and clinical results were excellent. Callotasis is considered to be a beneficial procedure for the treatment of brachymetatarsia.