Six patients with severe aplastic anemia treated with horse anti-human thymocyte globulin (ATG) and androgen. Four of these patients were only given ATG (ATGAMR), 16 mg/Kg/dose x 10 doses. The remaining two cases received an infusion of maternal HLA-haploidentical marrow cells following ATG therapy. One patient had a complete response, three had a partial response, one showed minimal improvement and two were non-responders. The two patients who received the additional haploidentical marrow cells showed a hematologic recovery sooner than the ATG alone cases. The toxicity of the ATG therapy was tolerable. Long term follow up of there patients and further studies of this treatment in aplastic anemia with pediatric age group are under way.