BACKGROUND: The period of time required for the diagnosis of a chronic illness depends on initial clinical symptoms and their perception by the patient and the physicians. The aim of this study was to describe the procedures of diagnosis of incident cases of Inflammatory Bowel Disease (IBD). METHODS: Patients reported by the Registry of inflammatory bowel disease of northern France (EPIMAD) in 1994 were included. Standardized questionnaires describing clinical history, patient behavior, medical consultations and examinations were collected by an interviewer practitioner from three sources: patients, general practitioners (GP) and gastroenterologists (GE). Patients were divided in 2 groups according to the time between symptom onset and diagnosis: more than 9 months or less than 9 months (D > 9 and D < or = 9). RESULTS: 258 patients were included: 144 Crohn’s disease (CD) (56%), 106 ulcerative colitis (UC) (41%) and 8 chronic unclassifiable colitis (CUC). Median time between symptom onset and diagnosis was 3 months, 196 (76%) patients belonged to the group D < or = 9 and 62 (24%) to the group D > 9. There was no difference between the 2 groups for initial clinical symptoms. The delay between symptom onset and the consultation to the GP and the GE was longer in the group D > 9: respectively 1 month vs 0 and 7.6 vs 2. Thirty-five percent of patients in the group D > 9 had consulted more than one GP vs 14% (p < 0.05). Diagnosis management by the GE was the same in both groups. Patients of group D < or = 9 had more often perceived their symptoms as serious (p < 0.05). CONCLUSIONS: Delay to diagnosis in a quarter of patients with IBD was more than 9 months. This later diagnosis was not due to patient management by the GE but rather to a longer delay to consulting the GP and between GP and GE referral. Patient interpretation of the symptoms could also explain the variability of this delay.