Acute graft-versus-host disease (GVHD) is one of the major complications of hematopoietic stem cell transplantation. Many variables including stem cell source, age of donor and recipient, preparative regimen and prophylaxis can impact the likelihood and severity of GVHD. The major portion of this review concentrates on risk factors, treatment and outcome, since here we may see differences between children and adults. Pathophysiology and manifestations/grading of acute GVHD are also briefly presented. An effort has been made to concentrate either on pediatric trials or look specifically at the pediatric subset of larger studies.