Multivariate analysis confirmed CYP3A5 intermediate and extensive metabolizers as an independent risk factor for acute GVHD (HR 3.5 [95% CI 1.5–8.3], p = 0.003) as well as clinically relevant acute GVHD (grades II-IV) (HR 4.5 [95% CI 2.4–8.6], p < 0.001). This evidence concerns the gene CYP3A5 and acute graft versus host disease.