Aim: To assess the effect of intravenously injected superparamagnetic iron oxide nanoparticle (SPION)-labeled adipose-derived stem cells (ADSCs) under an external magnetic field on the efficacy of ADSC transplantation in rats with spinal cord injury (SCI).Material and Methods:ADSCs were isolated from rats, labeled with SPIONs, and divided into magnetic and non-magnetic groups. A rat model of SCI was established, and the SCI rats were randomly divided into magnetic, non-magnetic, and control groups, with ten rats in each group. Rats in the magnetic and non-magnetic groups were injected with SPION-labeled ADSCs via the tail vein. Simultaneously, a 300 mT neodymium iron boron magnet was placed externally at the SCI site of rats in the magnetic group. One and two weeks after successful modeling, SCI rats were scored for the degree of SCI (Basso, Beattie, and Bresnahan [BBB] method) and assessed for histopathology of the spinal cord (hematoxylin-eosin [HE] staining), the number of ADSCs at the SCI site (Prussian blue staining), and growth-associated protein-43 (GAP-43) expression in the spinal cord tissues.Results:One and two weeks after modeling, the BBB scores were highest in the magnetic group, followed by the non-magnetic group, and lowest in the control group. HE staining showed that the histopathological manifestations of the spinal cord in the magnetic group were somewhat improved compared with those in the non-magnetic and control groups. Two weeks after modeling, Prussian blue staining revealed that ADSCs were significantly higher in the spinal cord tissue of the magnetic group than in the non-magnetic group. One and two weeks after modeling, western blotting elucidated that the magnetic group exhibited the highest GAP-43 expression.Conclusion:An external magnetic field at the SCI site in rats exerts a directional effect on SPION-labeled ADSCs, directing their migration and improving the efficacy of stem cell-targeted therapy for SCI.