Background: Inflammatory bowel disease (IBD) is often diagnosed in early adulthood in the working-age population and substantial work productivity losses among patients with moderate to severe disease have been reported [1,2]. The aim of this study was to examine the indirect burden among adult patients in the workforce (18–65 years of age) with Crohn's disease (CD) and ulcerative colitis (UC) in a moderate disease state. Methods: Electronic medical records of patients diagnosed with CD and UC between 2005 and 2014 in Uppsala County Council in Sweden were extracted (N=3,999) and enriched with data from the Swedish longitudinal integration database for health insurance and labour market studies (LISA). Patients were classified into the moderate disease state if (a) they were steroid dependent and (b) they had a Harvey-Bradshaw index score of 8–16 (for patients with CD) or partial Mayo index score of 2–4 (for patients with UC). Medical records that did not include sufficient information to designate reliable scoring were excluded and classification was based on steroid use alone. Indirect burden outcomes were assessed within 2 years after entering the moderate disease state. Annual productivity losses (sick leave and retirement) were collected from the LISA database. Indirect costs were calculated by multiplying the average annual number of sick leave days times the average annual Swedish salary, adjusting for gender. The average annual Swedish salary from 2014 was 350,400 SEK for women and 403,200 SEK for men (including legislated social fees of 47%). Results: In this study, 797 patients with CD (of 1,549) and 1,361 patients with UC (of 2,450) were classified as having moderate disease, 698 (88%) and 1,145 (84%) of which were aged between 18 and 65 years and included in the analysis. The average annual sick leave was long: 16 and 9 weeks for CD and UC, respectively (compared with an average 5.6 days/year in Sweden), which equaled an average annual cost of 86,440 SEK for patients with CD and 50,925 SEK for patients with UC. Few patients (17 CD and 21 UC) retired early, but the average age of retirement among those who did was 47 years for both patients with CD and those with UC. Conclusions: This study demonstrates high indirect costs in moderate IBD, which might be decreased with improved monitoring and treatment and should be taken into account when evaluating new therapies. This is particularly important as IBD often is diagnosed in early adulthood and the incidence now is rising.