Introduction: A peripherally inserted central catheter (PICC) is widely used for long chemotherapy regimens or total parenteral nutrition. However, spontaneous migration of the catheter into the azygos vein after satisfactory initial placement has occurred in rare cases. Methods: We discuss three such cases in esophageal cancer patients. Results: In two patients, the migrated catheters were found during surgery and were repositioned without complications. However, in the third case, the migrated catheter had to be removed to avoid severe complications, as the catheter and the azygos vein were ligatured during operation without notice. Conclusions: Migrations might be related to the material properties of silicone PICCs, the short insertion length, the left-sided placement, the changes of thoracic pressure and the intraoperative traction by thoracic surgeons. In conclusion, we recommend routine checks before cutting off the azygos vein during the operations for esophageal cancer patients with left-sided PICCs. © 2015 Wichtig Publishing.