It is known that the Salter-Harris type I and II fractures of the distal tibial epiphysis usually For resolving problems of delayed union and non-union of long bones, many efforts was made such as autogenous graft, allogenic or artificial bone graft and electrical stimulation, but there were many complications and not sufncient fracture healing process. The purpose of this study was to investigate the effect of autograft with bone marrow on the repair or bone formation of delayed union by the serial radiogram and clinical examination. We evaluated thirty nine patients which had been treated for long bone fracture, to whom bone marrow injection was made between 3 months and 13 months after adequate fixation(average.4.8months). After bone marrow injection, clinical follow up period was from 15 months to 35 months(average 26.7months). The age distribution was from 18 years to 84 years(average 42). A total of 100- 150cc of marrow was injected at the nonunion site immediately after aspiration under the C-arm. Of 39 cases, there were improved bone healing process of 30 cases(77%) by radiographically and clinically, Of 9 cases without improvement, 5 cases were due to loosening of external fixator, 2 cases was due to chronic osteomyelitis and other 2 cases was unknown origin. No serious complications were observed other than no improvement. Although percutaneous bone marrow injection does not promote healing more rapidly than would standard operative bone grafting, it has many distinct advantages over the latter. It is safe, easy, and time saving. It is economical and involves minimal trauma. It can be done under local anesthesia and avoids the risks of general anesthesia, infection and surgery. It can be done in cases which are not fit for open bone grafting because of poor condition of the skin.