Background and study aims: Although capsule endoscopy has become a central diagnostic tool for small-bowel evaluation, retention of a capsule remains a major concern. This study attempted to investigate the incidence and clinical outcomes of capsule retention, and to determine the factors predictive of spontaneous capsule passage after retention. Patients and methods: Through a nationwide multicenter survey, we retrospectively reviewed the records of 1291 patients who had a capsule endoscopy between February 2002 and July 2006 in Korea. Clinical and procedural characteristics and postprocedural outcomes were analyzed for the cases with capsule retention. Results: Capsule retention occurred in 2.5% of total cases (32/1291). The major diseases accompanying capsule retention were Crohn's disease, malignant tumors, and tuberculous enterocolitis, in decreasing order. In 11 of the 32 patients (34.4%), early surgical or endoscopic interventions were instituted for diagnosis or treatment of diseases before retention symptoms developed. The remaining 21 (65.6%) patients initially received medical treatments. Of these, 10 (31.3%) ultimately underwent surgical intervention due to the development of symptoms of intestinal obstruction or medical treatment failure. The other 11 (34.4%) eventually passed the capsule. The presence of a larger lumen diameter (greater than two-thirds of the capsule diameter) at the stricture site was associated with spontaneous passage. Conclusions: Our large-scale study suggests that retention occurs infrequently during capsule endoscopy. Moreover, a retained capsule might indicate the best intervention for the offending pathology, or it may spontaneously pass in the long run, particularly in patients with less small bowel stricture.