The effect of neuromuscular blocking agents (NMBAs) is characterized by a wide variability. Suchvariability is partly due to the differences in the pharmacological properties of the various relaxants used,partly due to differences in patient characteristics (age, gender, body composition, concurrent diseases andmediation etc), and partly to the type and depth of the anesthetic administered. Variability in effect leadsto unpredictable duration of neuromuscular blockade. Many studies have, despite a shift toward the use ofintermediately long-acting relaxants, demonstrated that residual paralysis is present at the end of surgeryand in the recovery room.It also has been demonstrated that residual paralysis leads to increasedpostoperative morbidity and mortality.Therefore many anesthetists routinely reverse neuromuscularblockade with the cholinesterase inhibitors neostigmine or pyridostigmine.