The authors report an extremely rare case of a patient with acromegaly who had unilateral enlargement of an atlas facet resulting in cord compression and progressive quadriparesis. Although unilateral atlas facet enlargement has been identified in the literature in cases of spondylosis and as a component of congenital malformation, its association with acromegaly has not previously been reported. Resection of the offending facetal bone and atlantoaxial fixation resulted in rapid neurological recovery.