We have demonstrated that high CD3+ (>347 × 10^6/kg) and CD34+ (>8.25 × 10^6 /kg) cell dose content in the grafts is an independent prognostic factor associated with higher probability of severe acute GVHD grades II-IV and III-IV for CD3+ and grades III-IV for CD34+ cell dose, respectively. This evidence concerns the gene CD34 and acute graft versus host disease.