Duane's retraction syndrome (DRS) is a congenital eye movement disorder characterized by adduction deficiency, abduction limitation, globe retraction, and palpebral fissure narrowing on attempted adduction. In a case of unilateral DRS, the right side of the brainstem, cavernous sinus, and orbit were completely normal. The left abducens nucleus contained no cell bodies from motor neurons, but in its rostral portion, it contained several small cell bodies believed to be compatible with internuclear neurons. The left abducens nerve was absent. The left lateral rectus muscle was partially innervated by branches from the inferior oculomotor nerve.