Closure of refractory perineal Crohn's lesion. Integration of hyperbaric oxygen into case management. A case is reported in which a comprehensive program of hyperbaric oxygen (HBO), surgical debridement and reconstruction, and continuing medical management resulted in complete and sustained closure of an extensive perineal Crohn's lesion refractory to conventional medical and surgical management. It is emphasized that in this case healing occurred in the setting of previous removal of all diseased intestinal tissue and only with the combined use of all three treatment modalities. HBO may be a useful adjunct in the therapy of large nonhealing perineal lesions post-proctocolectomy in patients who are unresponsive to metronidazole or to immunosuppressant therapy or who experience limiting side effects from continued medical therapy. 