Abstract Objective To identify the risk factors for catheter migration and demonstrate possible mechanisms of this migration. Design Retrospective study. Setting Chang Gung Memorial Hospital, a tertiary medical centre in Taiwan. Patients Patients who underwent implantation of intravenous ports via the superior vena cava (SVC). Interventions Procedures involving catheter placement and re-intervention for catheter migration. Main outcome measures The anatomic location of the catheter tip was confirmed by plain chest X-rays (postero-anterior view). From these plain radiographs, the distance (in cm) between the carina and catheter tip and the angle (in degrees) between the locking nut and catheter were measured. Methods A total of 1542 procedures related to intravenous port implantation were retrospectively reviewed but only procedures involving implantation via the SVC were included in the analysis. The study group was composed of 31 interventions because of catheter migration, while the control group consisted of 1475 implantation and re-intervention procedures except those involving catheter migrations. Results Shallow catheter-tip location ( p  < 0.0001) and the presence of lung cancer ( p  = 0.006) were risk factors for catheter migration. Conclusions Shallow catheter-tip location and the presence of lung cancer are risk factors for catheter migration. Strategies that ensure low catheter-tip location and avoid increased thoracic pressure may be useful preventive measures.