AIM: To describe an Internet-based data acquisition facility for a European 10-year clinical follow-up study project of a population-based cohort of inflammatory bowel disease (IBD) patients and to investigate the influence of demographic and disease related patient characteristics on response rates.METHODS: Thirteen years ago, the European Collaborative study group of IBD (EC-IBD) initiated a population-based prospective inception cohort of 2 201uniformly diagnosed IBD patients within 20 welldescribed geographical areas in 11 European countries and Israel. For the 10-year follow-up of this cohort, an electronic patient questionnaire (ePQ) and electronic physician per patient follow-up form (ePpPFU) were designed as two separate data collecting instruments and made available through an Internet-based website.Independent demographic and clinical determinants of ePQ participation were analyzed using multivariate logistic regression.RESULTS: In 958 (316 CD and 642 UC) out of a total number of 1 505 (64%) available IBD patients,originating from 13 participating centers from nine different countries, both ePQ and ePpPFU were completed. Patients older than 40 years at ePQ completion (OR: 1.53 (95%CI: 1.14-2.05)) and those with active disease during the 3 mo previous to ePQ completion (OR: 3.32 (95%CI: 1.57-7.03)) were significantly more likely to respond.CONCLUSION: An Internet-based data acquisition tool appeared successful in sustaining a unique WesternEuropean and Israelian multi-center 10-year clinical follow-up study project in patients afflicted with IBD.