Intestinal graft-versus-host disease (GVHD) causes anorexia, vomiting, abdominal pain, and diarrhea. We investigated oral beclomethasone dipropionate (BDP), a potent, topically active corticosteroid, as therapy for this disease. Forty-two allogeneic marrow-graft recipients with biopsy-proven intestinal graft-versus-host disease of mild-to-moderate severity received BDP (8 mg daily) for up to 28 days. Weekly symptom scores, oral intake, and surveillance throat and stool cultures were compared with baseline values. Adrenal testing was performed serially in patients not receiving concurrent prednisone. Improvement was seen in appetite (P < 0.001), oral intake (P < 0.001), nausea (P = 0.013), and diarrhea (P = 0.02) over the course of therapy, and an overall beneficial response was observed in 72% of 40 evaluable patients. Surveillance cultures of throat and stool showed no increase in bacterial or fungal colonization over time. The adrenal axis became suppressed in 11 of 20 evaluable patients (55%) but suppression was not a prerequisite for clinical response, as 6 of 9 patients who retained normal adrenal function improved clinically. We conclude that oral BDP is a safe and effective treatment for mild-to-moderate intestinal graft-versus-host disease. Systemic absorption probably occurs, but adrenal suppression is not a prerequisite for clinical efficacy, suggesting that the biological effect is primarily topical. BDP should be further investigated as a topical therapy for intestinal GVHD.