OBJECTIVES:  The long term economic burden of diverticular disease is poorly understood compared to other gastrointestinal (GI) diseases. We evaluated the trajectory of expenditures and incremental differences between Diverticulitis (DV), Appendicitis (AP) and Irritable Bowel Syndrome (IBS) in a managed care organization (MCO). METHODS: A retrospective cohort study among patients diagnosed with DV, AP or IBS, between 01/01/2002 and 12/31/2012 was conducted. Direct medical expenditures were obtained by weighting resource utilization with nationally representative reimbursement values. Prior to diagnosis of the incident event (index date), patients were required to be health plan members continuously enrolled for ≥12 months (baseline); and at least 60 months post index. We identified medical expenditures (2016 USD) associated with inpatient (IP), emergency department (ED) and outpatient (OP) visits during one, three and five year periods, after the index date. Total expenditure was the sum of IP, ED and OP expenditure. A generalized linear model with log link and gamma distribution was specified which adjusted for the following covariates: age, race, sex, ethnicity, insurance type, and Elixhauser comorbidity. RESULTS: We identified total of 38,241 patients of which 65% had IBS, 23% had DV and rest had AP. The average adjusted cumulative total expenditure per patient, in year one was $16,502, $13,478, $8509; in year three was $52,205, $76,400, $56,438; and in year five was $115,754, $195,349, and $143,302 in AP, DV and IBS respectively. While the incremental difference between DV and AP was -$7,436 (-$8,043 to -$6,830) in year one; by year three, DV patients had $5,369 ($2,433 to $8,304) higher expenditure and the difference increased to $30,670 ($23,985 to $37,354) by the end of fifth year. CONCLUSIONS: The trajectory of expenditure associated with DV suggests that it exerts significantly more economic burden on per patient basis, as compared to other well studied acute GI diseases.