Tacrolimus is increasingly used for graft-versus-host disease (GVHD) prophylaxis and therapy in the allogeneic stem cell transplant (allo-SCT) setting. Pancreatitis, previously described as a side-effect of cyclosporine, has not been reported in allo-SCT recipients receiving tacrolimus. We present here a case of acute pancreatitis in a 28-year-old patient with chronic myelogenous leukemia (CML) who received an unrelated umbilical cord blood transplant (UCBT) and tacrolimus for GVHD prophylaxis. On day +31 post-transplant, she developed severe acute pancreatitis with multiorgan failure, from which she recovered completely. Tacrolimus was the probable cause of pancreatitis in this patient.