Radiofrequency neurotomy (RFN) of the medial branches of the dorsal rami is a successful method of treating facet joint pain. Documented serious complications are rare. We discuss the case of a 33-year-old woman with low back pain (LBP) who sustained a right L5 nerve root injury during RFN. The patient had several months of axial LBP after a motor vehicle collision. She had no relief after anti-inflammatory medications, physical therapy, L5-S1 interlaminar epidural corticosteroid injections, and a right sacroiliac joint injection. She then received bilateral L3 and L4 medial branch and bilateral L5 dorsal ramus blocks with excellent temporary pain relief. Subsequently she underwent bilateral L3 and L4 medial branch and bilateral L5 dorsal ramus RFN. Afterward, she noticed new right leg pain and paresthesias extending throughout the L5 dermatome. Electromyography and magnetic resonance imaging were normal and she was diagnosed with a right L5 sensory radiculopathy. The right leg symptoms were unresponsive to multiple medications. After a successful trial with a spinal cord stimulator, she underwent permanent stimulator placement. Afterward, she had 90% relief of her right leg pain and discontinued all analgesics. Irreversible injury of nontarget nerves is a possible complication of RFN, and can be avoided by following proper procedural protocol.