Objective To investigate the cl inical effect of MSCs transplantation derived from human umbil ical cord on bone nonunion. Methods From December 2005 to December 2007, 72 patients with traumatic bone nonunion were treated. Auto-il iac bone transplantation was used in 36 patients (group A), including 27 males and 9 females, aging (34.0 ± 2.1) years; including 18 cases of femoral fracture and 18 cases of tibia fracture; and the time of bone nonunion being (9.1 ± 1.7)months. Percutaneous MSCs transplantation derived from human umbil ical cord was used in 36 patients (group B), including 28 males and 8 females, aging (36.0 ± 1.6) years; including 18 cases of femoral fracture and 18 cases of tibia fracture; and the time of bone nonunion being (6.4 ± 1.9) months. There were no statistically significant differences in general data between two groups (P gt; 0.05). In group A, the site of bone nonunion was filled with relevant auto-il iac bone. In group B, the mixture of 6-8 mL platelet-rich plasma prepared by centrifugal izing venous blood and 1 × (106-107) P5 MSCs extracted from human umbil ical cord denoted by volunteers was injected into the region of bone nonunion with 0.2 g demineral ized bone powder. Results Incision healed by first intention in group A. No puncture, deep infection, rejection and general fever reaction occurred in group B. All patients in two groups were followed up for (13.2 ± 4.6) months. No loosening and breakage of internal fixation were observed in two groups. The motil ity and function of hip, knee and ankle were good. The time of bone union was (10.3 ± 2.8) months in group A and (5.6 ± 0.8) months in groups B, showing significant difference between two groups (P lt; 0.05). Conclusion The percutaneous MSCs transplantation derived from human umbil ical cord is more effective on bone nonunion than the traditional treatment, it is easily-to-operate, safe, rel iable, and rapid for union. It is one of effective methods in treating bone nonunion.