Patients with KIR/HLA mismatches had a higher probability of developing acute GvHD (57% vs. 33%; P = 0.04) (grade I-II: 27%; grade III-IV: 30%) compared to those with KIR/HLA matches (grade I-II: 12%; grade III-IV: 21%). This evidence concerns the gene KIR3DL1 and graft versus host disease.