We herein describe the cases of two patients with post-irradiation lumbosacral radiculopathy. The patients underwent postoperative radiation therapy to the abdomen due to testicular neoplasms 20 and 25 years prior to the onset of weakness, respectively. On physical examinations, asymmetric lower limb weakness and areflexia without apparent sensory loss were observed in both patients. Interestingly, artificial and squared atrophy of the skin and subcutaneous tissue, thought to correspond to the radiation fields, were observed in the lower back, and electromyography revealed selective motor axon loss localized to the lower extremities. The detection of skin changes in the area being irradiated is a valuable clue for diagnosing post-irradiation lumbosacral radiculopathy.