Objective To investigate the expression levels of serum interleukin-33(IL-33)and fecal cal-protectin in ulcerative colitis and to predict the prognosis of recurrence.Methods A total of 113 patients with ulcerative colitis admitted to our hospital from December 2019 to January 2022 were selected as the study participants.According to the stage of ulcerative colitis,70 cases were in active stage,and 43 cases were in remission stage.According to the severity,there were 33 severe cases,39 moderate cases,and 41 mild cases.According to the recurrence prognosis of patients with ulcerative colitis,they were divided into the recurrence group(38 cases)and the non-recurrence group(75 cases).Total 110 healthy subjects were selected as the control group.The expression levels of serum IL-33 and fecal calprotectin in patients with ulcerative colitis and the control group were compared,and the predictive value of serum IL-33 and fecal calprotectin in patients with recurrent ulcerative colitis was analyzed.Results The expression levels of serum IL-33 and fecal calprotectin in the control group were significantly lower than those in the active stage group and remission stage group(P<0.05).The expression levels of serum IL-33 and fecal calpro-tectin in the active stage group were significantly higher than those in the remission stage group(P<0.05).The expression levels of serum IL-33 and fecal calprotectin in the mild group were significantly low-er than those in the severe group and moderate group(P<0.05).The expression levels of serum IL-33 and fecal calprotectin in the moderate group were significantly lower than those in the severe group(P<0.05).The expression levels of serum IL-33 and fecal calprotectin in the non-recurrence group were signifi-cantly lower than those in the recurrence group(P<0.05).ROC curve analysis showed that when the AUC of serum IL-33 and fecal calprotectin were 0.714 and 0.623,respectively,the Joden index was the lar-gest.When the cutoff values were 130.03 and 517.68,respectively,the combined prediction AUC was 0.827(95%CI:0.737~0.918),sensitivity(77.4%),specificity(79.3%),positive predictive value(78.9%),negative predictive value(77.8%),which were higher than the single test of each parameter(P<0.05),and the prediction efficiency was the best.Conclusion The expression levels of serum IL-33 and fecal calprotectin are closely related to the disease activity level and prognosis of patients with ulcera-tive colitis,which can be used as biomarkers for clinical diagnosis and prediction of ulcerative colitis.