The roles of angiogenesis and angiogenic factors after allogenic hematopoietic SCT (HSCT) and during acute GVHD (aGVHD) are not known. Studies on pediatric patients are extremely scarce. Levels of angiopoietin-2 (Ang2) and vascular endothelial growth factor (VEGF) were analyzed from blood samples of 67 consecutive patients. The levels were correlated with aGVHD grades, routine laboratory parameters and outcome. Pre-transplant Ang2 values correlated with the occurrence of intestinal aGVHD (P=0.009), whereas post-transplant measurements correlated with the severity of skin and liver aGVHD (P=0.03, P=0.04, respectively). Pre-transplant levels of VEGF were associated with the occurrence of skin aGVHD (P=0.04), whereas post-transplant levels correlated to the severity of intestinal aGVHD (P=0.04). High Ang2 levels were associated with shorter EFS (P=0.039) and increased non-relapse mortality (NRM) (P=0.009). In conclusion, higher Ang2 levels predict higher NRM and, with coexisting high VEGF, also shorter EFS after pediatric HSCT. Our results suggest that both pre- and post-transplant levels of Ang2 and VEGF seem to correlate to the clinical state of the patient. However, the pathophysiology of this connection needs further studies.