ObjectiveTo observe the curative effect of marrow stem cell transplant on bone nonunion and bone defection.Methods140 patients were randomly divided into the group A (with auto-iliac bone transplant) and group B (with auto-marrow stem cell transplant). There were 70 cases in each group. All patients in two groups were treated by operation and inside and outside fixation.ResultsAfter treatment, the average cicatrization time of group A was (7.0±2.0) months, that of group B was (5.0±1.5) months, there was a significant difference between two groups( P<0.05). There were no obvious adverse reactions found during the treatment period.ConclusionCompared with the traditional bone grafting, treating bone nonunion and bone defection by auto-marrow stem cell transplant has obvious superiority with better curative effect, short course and no adverse reactions.