BACKGROUND/AIMS: Relapse in inflammatory bowel disease (IBD) is not predictable, although several factors have been suggested. The aims of the current study were to assess and compare the possible causes of clinical relapse as perceived by patients and parents. METHODS: Of 107 young (<35 years old) IBD patients, 26 patients who experienced recent (<3 month) relapse and their parents completed a questionnaire at the same time. Baseline characteristics and clinical manifestations were reviewed and the most common causes of relapse as perceived by patients and parents were compared. RESULTS: Median patient age was 22.5 years and the male to female ratio was 17:9. Crohn's disease was diagnosed in 23 patients and ulcerative colitis in the other three patients. Mean disease duration was 39.8+/-30.3 months. Eighteen (69.2%) patients experienced stress before relapse. Fifteen (57.7%) parents thought that their children experienced stress before relapse. Agreement between patients and parents for non-adherence to medication and stress was 100% and 73.1%, respectively. Stress was considered the most likely cause of relapse in both groups. Discordance rate between parents and patients with respect to main causes of relapse was 40.4%. CONCLUSIONS: Stress was perceived to be the most common condition noted before clinical relapse in young IBD patients and their parents. However, the discordance rate between patients and parents with respect to the main causes of relapse was 40.4%. This result suggests a considerable difference in terms of disease understanding between young IBD patients and parents.