Lithium, first used by Cade in 1949 for the treatment of mania, is now commonly used in several affective disorders. The precise mechanism of its action is not clearly understood but the side effects may be severe. Prolongation of succinylcholine and pancuronium which possible mechanism of interaction involves impaired acetylcholine synthesis and release at nerve terminal has been reported. The present report describes a case of prolonged neuromuscular blockade induced by succinylcholine in a manic depressive patient being treated with oral lithium carbonate.