The main limitation of capsule endoscopy is the risk of capsule retention. In patients with suspected Crohn's disease, however, this complication is rare, and if a small bowel stenosis is not reliably excluded, small bowel patency can be confirmed with the Pillcam patency capsule. We present two patients examined for suspected Crohn's disease who experienced significant symptoms from a retained patency capsule. Both patients had Crohn's disease located in the terminal ileum. In one patient, the patency capsule caused abdominal pain and vomiting and was visualized at magnetic resonance enterography 9 days after ingestion. Symptoms improved spontaneously. Another patient experienced small bowel perforation with severe peritonitis caused by an intact patency capsule wedged in a small bowel stricture. We conclude that the Pillcam patency capsule is an effective modality for securing small bowel patency prior to capsule endoscopy. However, it should be emphasized that delayed patency capsule degradation and symptomatic capsule retention is a rare but potentially severe complication which should be treated aggressively, either medically or endoscopically.