Experience with tacrolimus in combination with mini-methotrexate to prevent graft-versus-host disease (GVHD) is limited in pediatric patients undergoing allogeneic blood or bone marrow transplants. We reviewed our use of this regimen in 24 pediatric patients who had 26 blood or marrow transplants. Acute GVHD occurred in 7 patients (4 unrelated donor transplants, 3 matched sibling transplants; 5 grade I to II, 1 grade III, and 1 not classifiable). One patient had extensive chronic GVHD (matched sibling transplant). In our experience, tacrolimus with mini-methotrexate has been well tolerated with minimal toxicity.