Abstract Background Acute severe ulcerative colitis (ASUC) is a life-threatening condition which requires quick decision making and urgent treatment. To facilitate this process, it is essential to identify patients at a high risk of emergency colectomy. The aim of this study is to identify predictors for emergency colectomy in patients with ASUC. Methods A retrospective study of 121 patients admitted with ASUC to a single gastroenterology centre between 2010 and 2020 was performed. Clinical and demographic data, laboratory and endoscopic examinations results were analysed as potential predictors of colectomy. Albumin and C-reactive protein (CRP) levels were recorded at baseline and at the 3rd day after intravenous steroids (IVS) initiation. Results 119 patients initially received IVS, while 2 patients with suspected intestinal perforation underwent emergency colectomy on the first day. 64 (53%) were women, with a median age of all patients of 33 (IQR 27-49) yrs. 15 (12.4%) patients admitted with ASUC underwent colectomy, while mortality rate during hospitalization was 1.7%. During the entire follow-up period, with a median duration of 46.5 months (23-88.25), colectomy was performed in 19 (15.7%) patients. Overall, in the study group, colectomy rate at 1 month, 3 months and 2 years were 12.4%, 12.4%, and 14.0%, respectively. Assessing further outcomes after colectomy, during the follow-up period, 13 (68.4%) achieved clinical remission, 1 died during the operation, and 5 (26.3%) patients still have an active course of the disease requiring immunosuppressive treatment. When comparing patients in the colectomy group (n=13) with patients who avoided colectomy during this hospitalization (n=105), no significant differences were found in age, sex, duration of illness, body mass index, endoscopic activity, the use of prednisolone or azathioprine prior to admission or previous treatment with biologics. The presence of cytomegalovirus and Clostridium difficile infection was also not associated with a higher risk of colectomy. Significant differences between the groups were found comparing the laboratory findings: the strongest predictor of colectomy was the CRP/albumin ratio at day 3 after IVS initiation (median value was 1.26 (0,81-3,26) in colectomy group vs. 0,64 (0,25-1,36) in non-colectomy group, p<0.001). The difference was also observed when comparing albumin (median 26 (24-28) vs. 29 (27-32), p=0.012) and CRP (median 33 (25-83) vs. 16 (8-37), p=0.003) levels separately on the 3rd day, while at baseline there was no significant differences in laboratory findings. Conclusion A low serum albumin level, higher CRP and CRP/albumin ratio are predictive factors of emergency colectomy in ASUC patients.