Oral involvement of chronic graft-versus-host disease (GvHD) is a most distressing and disabling complication of hematopoietic cell transplantation, for which systemic immunosuppression as well as topical corticosteroid treatment may offer only limited symptomatic relief. Here we report encouraging preliminary results with the application of tacrolimus (FK-506) as a 0.1% ointment in three patients with severe oral chronic GvHD, heavily pretreated without success, who experienced rapid, consistent, complete or at least marked, subjective and objective improvement with topical tacrolimus.