BACKGROUND: Use of complementary and alternative medicine (CAM) is common among IBD patients (1). The CAM modalities used include a wide specter of health care practices and therapies (2). In a previous study from this population, we found that almost one third of the patients used CAM 10 years after diagnosis (3). The aim of this follow-up study was to assess CAM use in IBD patients 20 years after diagnosis. METHODS: The Inflammatory Bowel South-Eastern Norway (IBSEN) study is a population based study with a prospective design. From January 1990 to December 1993, all newly diagnosed patients with IBD from a well defined area in South Eastern Norway were included in the cohort. The 20-year follow-up was conducted between 2011 and 2014 and included a structured interview, a review of patient records, a clinical examination, laboratory tests, and a questionnaire regarding CAM use. RESULTS: Of the 599 invited to attend the 20-year follow - up visit, 78.5% (UC = 314, CD = 156) participated in the follow- up study, whereof 93% (UC = 293 and CD = 146) completed the CAM questionnaire, 49% men. In total 122/439 (28%) reported use of CAM for their IBD, and 6% reported current CAM use. A significantly higher proportion women than men (60% vs 40%, P = 0.02) reported to use CAM. CAM users were younger (49 years) than the non-users (56 years), P < 0.001. A significantly higher proportion CD patients compared to UC patients (34% vs 25%, P = 0.04) reported CAM use. Treatment with CAM occurred more frequently in patients with more than one relapse the last year than in patients in remission (35% vs 21%, P = 0.003). The 3 most commonly used types of CAM were acupuncture 63/122 (52%), homeopathy 49/122 (40%) and herbal medicine 47/122 (39%). The 2 most common reasons for using CAM was as (1) a supplement to conventional treatment (41%) and (2) lack of effect from conventional medicine (32%). CONCLUSION(S): One third of the IBD patients reported CAM use 20 years after diagnosis. Prevalence of CAM use was comparable in the 10-year and 20-year follow- up. CAM use was more common among women, in younger patients, in UC patients, and in those with disease activity.