We reviewed the results of metatarsal lengthening of ten brachymetatarsus by callotasis using the mini-Orthofix (Orthofix M-100). There were three boys and three girls, with an average age at operation of 10 years and 10 months. Lengthenings were done on six fourth metatarsus, three first metatarsus, and one third metatarsus. The causes of the brachymetatarsia were congenital in eight, post-infectious in one, and post-traumatic epiphyseal damage in one metatarsus. Average amount of lengthening were 15.8mm (10-20mm), with an average percentage increase of 36.496 (20-43%). Target of lengthening was achieved in all patients. Average healing index was 2.62 months/cm(2.3-3.4 months/cm). The cosmetic and functional outcomes were very satisfactory in spite of some skin pigmentation residuae at the screw sites. In summary, callotasis using mini-Orthofix is a useful method of metatarsal lengthening, which obviates the need of bone graft and permits early weight-bearing during the treatment period.