Background Although the outcome of hyper-acute and acute rejection in cardiac transplantation has been improved for last decade, the mortality rate from unidentified cause did not decline in rate of graft failure in pediatric cardiac transplantation. Recently, antibody-mediated rejection (AMR) has revealed the one of risk factors for graft failure in cardiac transplantation, but AMR is not established in diagnosis and treatment. We aim to report outcome of managing suspected AMR in pediatric cardiac transplantation. Method and results Between March, 2001 and August, 2011 we retrospectively reviewed medical record of 36 patients undergone allograft cardiac transplantation. AMR were suspected in 7 patients and 6 patients were diagnosed by C4d-immunohistochemical staining. They presented graft dysfunction without evidence of significant cellular rejection by endomyocardial biopsy or vasculopathy by intravascular ultrasonography. Initially they were treated with methylprednisolone pulse therapy and then plasmaphereses were followed in patients with persistent graft dysfunction. Median period at diagnosis of AMR were 13 month (range: 12-62) after transplantation. 3 out of 6 patients who were positive for C4d had plasmapheresis for persistent graft dysfunction despite of methylprednisolone pulse therapy. After plasmapheresis, 2 patients were recovered and 1 patient expired for irreversible graft failure. Rest 3 patients were responsive to methylprednisolone therapy alone. Conclusion We found AMR resulted in graft failure and mortality in subacute phase and AMR is difficult to be diagnosed and to be managed. AMR need to be evaluated in patients presenting graft dysfunction with unidentified mechanism. This is more important for pediatric population who has more life expectancy.