Ulcerative colitis (UC) is a form of inflammatory bowel disease (IBD) that is characterized by pathologic inflammation and ulcerations in the colon resulting in bloody bowel movements, anemia and malnutrition with a relapsing and remitting course. Hospitalization for disease flares is common in cases with a severe phenotype and requires intensive monitoring and intravenous therapies; readmission within 30 days occurs in up to 18% of patients, for which the most common indication is disease flare. Readmissions are associated with increased morbidity, mortality, as well as costs, but the importance of post-discharge follow-up with a gastroenterology specialist as well as the optimal interval are unknown. We conducted a retrospective cohort study of 223 patients with medically-managed ulcerative colitis who were admitted to the Stanford University Hospital between 2010 and 2020. We included adult patients with UC who were admitted for a UC flare. Patients with a colectomy by time of discharge or who were diagnosed with Clostridium difficile infection at the index hospitalization were excluded. The primary outcome was time to readmission for a GI-related indication, and the primary predictor of interest was follow-up with a gastroenterology provider. Patients were censored 180 days after discharge. At the index hospitalization, 60.9% had pan-colitis, and 87.9% had moderate-to-severely active endoscopic disease. Follow-up occurred within 7 days in 65 patients (29%), within 30 days in 153 patients (68.7%), and within 180 days in 198 patients (89%). Readmission occurred in 57 patients (25%); 31 happened within 30 days for a 30-day readmission rate of 13.9%. In the Cox proportional hazards model adjusted for age, sex, and albumin level using follow-up with a gastroenterology provider as a time-dependent predictor, follow-up was associated with fewer readmissions (hazard ratio 0.42, 95% confidence interval 0.22-0.81, p=0.009). In particular, follow-up within 7 days after discharge (occurred in 65 patients) was strongly associated with reduced risk of subsequent readmission (HR 0.24, 95% CI 0.09-0.69, p-0.008). Via the log-rank test for trend, earlier follow-up was found to be associated with fewer less readmissions (p