OBJECTIVES: Examine inpatient hospital utilization, following colectomy, in patients with ulcerative colitis (UC) covered by Medicare. METHODS: A retrospective analysis was conducted using claims from the Medicare Standard Analytic Files (SAF) 5% sample database between January 1, 2001 and December 31, 2005. Patients with UC were identified using diagnostic codes (ICD-9 codes 556.x) and were limited to those with a procedure code indicating colectomy (45.7x), and a diagnosis of UC prior to that date. Patients with a subsequent diagnosis of Crohn's disease were eliminated from this analysis. The first procedure was chosen if the beneficiary had multiple 45.7x procedures (these are partial excisions, so a beneficiary could have multiple procedures over time). The study design consisted of a 12-month pre- and 12-month post-colectomy period during which continuous enrollment was required. Inpatient hospital costs and resource utilization were evaluated 12-months before and 12-months after the quarter in which the colectomy occurred. All costs are presented in 2005 US dollars. RESULTS: A total of 905 patients with UC who had a claim for colectomy were included in the analysis. Total inpatient costs ($19,778 vs. $23,765) and average length of stay (ALOS) (15.2 days vs. 18.3 days) increased following colectomy, while mean number of admissions did not increase significantly. The same trend was seen in UC-related costs ($6,957 vs. $12,422) and lengths of stay (7.6 days vs. 11.7 days). CONCLUSION: Inpatient hospital utilization and subsequent costs increased during the 12-month period following colectomy in the Medicare population. Additional analyses are needed to determine the extent of these services and reasons for increased inpatient utilization.