This study evaluated the safety, immunogenicity, and hemostatic effect of recombinant human Thrombin (rThrombin), in patients undergoing skin grafting for burns. This was a phase 2 multiple site, single-arm, open-label study in patients receiving partial- or full-thickness autologous grafts. rThrombin was applied using a spray applicator to newly excised wounds of 1 to 4% body surface area at 5 minutes intervals for up to 20 minutes, after point source bleeding was stopped. Adverse events, skin graft survival, and formation of anti-rThrombin antibodies were measured at baseline and Day 29. There were no deaths or study drug discontinuations. Adverse events occurred in 63 of 72 patients (88%), and were typical of sequelae of skin grafting. Hemostasis was achieved within 20 minutes after application of rThrombin in 65 of 71 patients (91.5%). Skin graft failure occurred in 4 patients (6%). At the day 29 evaluation, for those patients who returned, 88.9% had > or =90% graft survival. One patient (1 of 70, 1.4%) had specific, low titer antibodies to rThrombin at baseline, but no increase in titer posttreatment; a second patient (1 of 62, 1.6%), developed antibodies to rThrombin at day 29. None of the antibodies neutralized native human thrombin. In excised burn wounds, hemostasis at 20 minutes was achieved in 91.5% of patients and skin graft survival was excellent. There was a low rate of antibodies to rThrombin at baseline (1.4%) and a low rate of anti-rThrombin antibody formation at day 29 (1.6%). rThrombin was well tolerated when administered with a pump spray.