Abstract： Objective To observe the effect of hyperbaric oxygen (HBO) coupled with sulfasalazine on ulcerative colitis,and to investigate safe and effective methods for the treatment of ulcerative colitis.Methods Two hundred and seventy-six cases of ulcerative colitis were randomly divided into the control group receiving only sulfasalazine (135 cases) for 8 weeks and the HBO group (141 cases) treated with HBO combined with sulfasalazine for 8 weeks.Observations were made on the improvement of clinical symptoms and outward appearance under the endoscope in the 2nd,4th and 8th weeks respectively.Results Significant effective rate and total effective rate for the HBO group accounted for 84.4％ and 100％,which were significantly higher than those of the control group (44.4％ and 76.3％ ).There were statistical significance between the two group (P＜ 0.05 ).Conclusions HBO coupled with sulfasalazine in the treatment of ulcerative colitis could produce quicker and more significant results,and with fewer side-effects.