Background: We aimed to characterize the trends of prognosis in Ulcerative Colitis (UC) and Crohn’s Disease (CD) in a Chinese tertiary hospital. Methods: A 30-year retrospective cohort analysis was conducted at Peking Union Medical College Hospital. Consecutive patients newly diagnosed with UC or CD from 1985 to 2014 were included. The primary outcome was in-hospital mortality. Second outcomes included surgery and length of stay in hospital. Pearson correlation coefficient was performed to determine the relationship between time and prognosis. Multivariable logistic regression analysis was performed to determine the risk factors for in-hospital mortality and surgery. Results: In total, 1467 patients were included in this study (898 cases with UC and 569 cases with CD). Annual admissions of UC and CD rose significantly over the last 30 years (UC, r=0.918, P<0.05; CD, r=0.898, P<0.05). Decreased in-hospital mortalities were observed in patients with UC and CD (UC, from 2.44% to 0.27%, r=-0.827, P<0.05; CD, from 12.50% to 0.00%, r=-0.978, P<0.05). A decreasing surgery rate was observed in patients with CD (r=-0.847, P<0.05) while an increasing surgery rate was observed in patients with UC (r=0.956, P<0.05). Shortened average lengths of stay in hospital were observed both in patients with UC and CD (UC, from 47.83±34.35 days to 23.58±20.05 days, r=-0.970, P<0.05; CD, from 65.50±50.57days to 26.41±18.43 days, r=-0.913, P<0.05). Toxic megacolon, sepsis shock were independent risk factors for in-hospital mortality in patients with UC. Intestinal fistula, intestinal perforation were independent risk factors for in-hospital mortality in patients with CD. Conclusions: In this cohort, the admissions of patients with UC and CD were increased with a significantly improved prognosis during past 30 years.