This prospective clinical study identified patients in whom paralysis developed after lumbar surgery. To determine whether patients with psychogenic paralysis could be identified using noninvasive techniques. Before the advent of transcranial magnetic stimulation, no clinically applicable, noninvasive technique was available to confirm the integrity of the corticospinal tract. Patients with suspected postoperative psychogenic paralysis were evaluated by clinical examination and neurophysiologic work-up, including transcranial magnetic stimulation. Six patients with psychogenic paralysis were identified in a 15-month period. In each case, motor evoked potentials could be demonstrated from the affected muscle(s), thus obviating the need for further invasive imaging or surgical exploration. Transcranial magnetic stimulation is a reliable, painless, and noninvasive technique for demonstrating structural integrity of the corticospinal tracts.