Objective To explore the clinical efficacy of human umbilical cord mesenchymal stem cells transplantation in the treatment of late traumatic epilepsy.Methods Thirty-one patients with late traumatic epilepsy were transplanted with human umbilical cord mesenchymal stem cells and the clinical effect was observed.Results During 18.7 months of follow-up,21 patients were found to be completely seizures-free or with only aura(ClassⅠ),5 patients only had rare seizures(ClassⅡ,less than 3 times a year).And obvious improvement was achieved in 4 patients(ClassⅢ,at least 75% seizures reduction),no significant change was observed in 1 case(ClassⅣ,less than 75% seizures reduction).The satisfactory rate was 83.87%.Conclusion The human umbilical cord mesenchymal stem cells transplantation in the treatment of late traumatic epilepsy can result in a satisfactory clinical effect.