This prospective, randomized, double-blind, placebo-controlled study evaluated the efficacy of palifermin to reduce the incidence of severe (grade 3-4) acute GVHD after myeloablation and allo-SCT. Adults who received allo-SCT for hematologic malignancies received placebo or palifermin 60 μg/kg daily on three consecutive days before conditioning and a single dose of 180 μg/kg after conditioning, but often 1 or 2 days before allo-SCT. Subjects received MTX (plus CYA or tacrolimus) on days 1, 3, 6 and 11. Acute GVHD was evaluated once weekly and oral mucositis was evaluated daily. Subjects were randomly assigned to placebo (n=78) or palifermin (n=77). Conditioning included TBI in approximately half of the subjects (48% placebo, 51% palifermin). The primary efficacy end point, subject incidence of grade 3-4 acute GVHD, was similar between treatment groups (17% placebo, 16% palifermin). Grade 3-4 oral mucositis (73% placebo, 81% palifermin) and other secondary efficacy end points were similar between treatment groups. The most commonly reported treatment-related adverse events were skin/s.c. events such as rash, pruritus, and erythema. This exploratory study of acute GVHD after myeloablation and allo-SCT did not provide evidence of a treatment effect with this dosing regimen of palifermin.