BACKGROUND: Comanagement of surgical patients has increased, but information regarding detailed characteristics of patients receiving comanagement during hospitalization for colorectal cancer (CRC) surgery is lacking. OBJECTIVE: To examine the use of and characteristics associated with comanagement of patients hospitalized for CRC surgery. DESIGN: This study used a population-based cross-sectional design. SETTING: We used the linked 2000 to 2005 Surveillance, Epidemiology, and End Results and Medicare claims data. PATIENTS: We included 37,065 patients aged 66 years or older, hospitalized for definitive CRC surgery following stage I to III diagnosis. MEASUREMENTS: The outcome of interest was comanagement during hospitalization for CRC surgery, and we examined the association between several patient and hospital characteristics. Comanagement was defined as having a relevant physician (ie, internal medicine hospitalist/generalist) submit a claim for evaluation and management services on 70% or more of the days of hospitalization of the patient. RESULTS: During hospitalization for CRC surgery, 27.6% of patients were comanaged, but this percentage varied widely across hospitals (from 1.9% to 83.2%). Several patient and hospital characteristics were associated with the use of comanaged care, of which important characteristics included older age at diagnosis, presence of comorbidity, emergency surgery, and hospital volume. CONCLUSIONS: Extensive variability existed in comanagement use across patients and hospitals, likely reflecting the lack of evidence for its clinical effectiveness.