Stress is often perceived by patients with inflammatory bowel disease (IBD) as the leading cause of their disease. The aim of this study was to assess whether stress, evaluated through life event (LE) occurrence, is associated with IBD onset. Incident cases of IBD, including 167 patients with Crohn's disease (CD) and 74 with ulcerative colitis (UC), were compared with two control groups, one of 69 patients with acute self-limited colitis (ASLC) and another of 255 blood donors (BDs). Stress was assessed using Paykel's self-questionnaire of LEs. Only LEs occurring within 6 months before the onset of symptoms in IBD cases and ASLC controls and before blood donation in BD controls were registered. Anxiety and depression were assessed using Bate's and Beck's questionnaires, respectively. In univariate analysis, occurrence of LEs was more frequent in the 6-month period prior to diagnosis in CD cases than in UC cases or either control group. After adjustment for depression and anxiety scores as well as other characteristics such as smoking status and sociodemographic features, this association appeared no longer significant. No associations were noted between occurrence of LEs and onset of UC relative to controls. Despite its separate association with CD, LE occurrence does not appear to be an independent risk factor for IBD onset.