Lumbar plexopathy is characterized by an abrupt onset of sensory disturbances, weakness, and loss of deep tendon reflexes of lower extremities. The various causes of lumbar plexopathy include trauma, infections, space-occupying lesion, vascular diseases, metabolic diseases, and the use of drugs such as heroin. Postoperative rhabdomyolysis occurs secondary to prolonged muscle compression due to surgical positioning. Herein, we report a case of lumbar plexopathy, complicating an injury to the paraspinal muscle and iliopsoas muscle that occurred in the flexed lateral decubitus position following radical nephrectomy.