Disorders of the brachial and lumbosacral plexuses are rare mimickers of spinal cord and root diseases. The clinical manifestations consist of pain, weakness, and sensory loss in the affected limb. The plexuses may be injured by several mechanisms, including trauma, inflammation, structural compression, or infiltration. The use of careful electrodiagnostic testing and neuroimaging studies, in addition to the identification of clinical clues, is important in diagnosing plexopathies and determining etiology. Despite identification of the etiology of plexopathies, treatment is often limited. Treatment of the underlying cause, as well as supportive and symptomatic treatment, may lead to improvement of neurologic function.