A 73-year-old woman was admitted with severe burning pain, hyperesthesia, and weakness in the right lower extremity. The patient had undergone radio- and chemotherapy after surgery for cervical cancer 17 years earlier. We diagnosed radiation-induced lumbosacral plexopathy because of conduction block in the deep peroneal nerve and myokymic discharge in the tibialis anterior muscle. Pelvic computed tomography and magnetic resonance imaging ruled out recurrent tumor and nerve-compressing lesions. Although radiation-induced lumbosacral plexopathy is usually characterized by lower motor neuron syndrome, we report a rare case presenting with severe pain and hyperesthesia.