OBJECTIVES This burden of illness study was conducted to assess the 12-month resource utilization and health care costs, along with the major drivers of those costs, associated with an incident diagnosis of colorectal cancer (CRC). METHODS An analysis of incident CRC patients identified using a claims database, was performed, for 2005, 2006, and 2007. CRC patients and the age and gender matched comparator group (1:4) for each year, were required to have continuous enrollment in a plan and no CRC diagnoses during the 18 months prior to the first diagnosis of CRC in the year. The CRC and comparison groups were each described in terms of their health care service use and healthcare costs, which were compared, using nonparametric Wilcoxon rank-sum tests, with mean values reported here for 2007. RESULTS There were 13,673 patients diagnosed with CRC in 2007, in this database, and we selected 54,688 controls. The mean healthcare cost for these patients diagnosed with CRC was $36,558 vs. $6,407 for controls; p<0.001. The primary drivers for this nearly 6 times greater cost difference between the 2 groups were: hospitalizations ($15,996 vs. $1,959; p<0.001); prescription drugs ($6,689 vs. $1,382; p<0.001); radiology tests ($2,312 vs. $333; p<0.001); and physician visits ($1,665 vs. $617; p<0.001). Resource utilization over the 12-month period showed that the patients with CRC, when compared to the control group, had a significantly greater (p<0.001) mean number of hospitalizations (0.9 vs. 0.2); prescriptions drugs (33 vs. 17); radiology tests (9 vs. 2); and physician visits (12 vs. 7). The results were similar for analyses conducted on 2006 and 2005 data. CONCLUSIONS The significantly higher 12-month resource utilization and healthcare costs noted in patients diagnosed with CRC, compared to age and gender matched controls, are primarily driven by an increased need for hospitalizations, prescription drugs, radiology tests, and physician visits.