Objectives: The objective of this study was to evaluate the accuracy, safety, and efficacy of magnetic resonance (MR)-guided periradicular nerve root injection therapy using an open 1.0-T magnetic resonance imaging (MRI) system with fast dynamic imaging. Materials and Methods: Between April 2008 and November 2011, a total of 249 MR-guided periradicular nerve root injections were performed in 141 patients experiencing lumbosacral radicular pain. All interventions were performed in an open 1.0-T MRI system. An interactive proton-density-weighted fast spin-echo sequence was used for real-time guidance. An in-room monitor, a wireless MR mouse for operator-controlled multiplanar imaging, a flexible surface coil, and an MR-compatible 20-G needle were used. Informed consent was obtained from all patients. Clinical outcome was evaluated through clinical follow-up and a questionnaire before injection therapy (baseline) and 6 months after using a numeric visual analog scale. Results: All procedures were technically successful. No major complications occurred. At 6 months, of the 103 patients (197 injections; 57 men, 46 women; mean age, 49.5 years; range, 20-80) who enrolled in the outcome analysis, 14.6% reported complete remission of radicular pain; 53.4%, significant relief of pain; 22.3%, mild relief; and 9.7%, no relief of pain. We found a significant decrease of the visual analog scale score from the preintervention compared with the follow-up after 6 months (P < 0.001). No significant difference in the outcome was observed between the patients with degenerative foraminal stenoses and the patients with herniated disks. Conclusions: Magnetic resonance fluoroscopy-guided periradicular injection therapy for the lumbosacral spine under open 1.0-T MRI guidance is accurate, safe, and efficient in the symptomatic treatment of radicular pain. This technique may be a promising alternative to fluoroscopy-or computed tomography-guided spinal injections in the lumbosacral region, especially for young patients and patients undergoing serial therapeutic regimens.