Adult-onset muscular dystrophy is an inherited myopathy characterized by a variable degree of progressive muscle weakness and degeneration. Although not usually fatal, significant muscle weakness results in an up-regulation of acetylcholine receptors on the less responsive postjunctional muscles. The resulting profound potassium release when these receptors are stimulated by the depolarizing muscle relaxant succinylcholine can result in potentially fatal cardiac arrhythmias. We report a case of electroconvulsive therapy safely administered in a 61-year-old man with adult-onset muscular dystrophy requiring muscle relaxation with rocuronium.