Objective: Both constipation (C) and irritable bowel syndrome plus C (IBS+C) are known to be very costly. However, it is unknown whether the costs of C are driven by the same factors that drive the costs of IBS+C. We aimed to assess the cost of illness (COI) for C without and with IBS (IBS+C) by point of service. Methods: A retrospective analysis was conducted using multiple US-based employers' health claims data from 2001-2005. Data included medical, pharmacy, payroll, and demographics. ICD-9 Codes were used to include employees in the C cohort: 564.0 (Constipation), 564.00 (Unspecified), 564.01 (Slow Transit), and 564.09 (Other). Employees with C and an ICD-9 for IBS (564.1x) at any time were included in the IBS+C cohort. Propensity-scores based on demographics, job-related variables, region, existence of medical claims, and Charlson Comorbidity Index Score were used to match five C to each IBS+C cohort employee. For both cohorts, the index date was the date of the first claim for the condition. Per member per month (PMPM) costs (adjusted to 2006 US$) were compared for each category based on claims from: doctor's office, inpatient hospital, outpatient hospital/clinic, emergency department (ED), laboratory, other locations, and pharmacy. Costs were compared between groups before diagnosis, after diagnosis, and change (before – after). Results: Data were available for 203 persons with IBS+C and 1015 propensity-score-matched C subjects. Between group comparisons (before, after, and change) were all non-significant except for Rx drugs ($19 higher for IBS+C, P<0.05) and other ($8 higher for C, P<0.05) in the after period as well as the change for Rx drugs ($16 higher for IBS+C, P<0.05). Within groups, costs for Rx Drugs significantly increased in both cohorts and outpatient and ED significantly increased for the C cohort. Conclusion: Patients with constipation and IBS+C incur similar costs throughout the health care system.