A 0.9 train-of-four ratio, measured at the thumb, is currently considered to reflect adequate recovery of neuromuscular block. Recent studies have documented that a train-of-four ratio <0.9 is associated with a decrease in chemoreceptor sensitivity to hypoxia and with a functional impairment of the pharyngeal muscles. These residual effects of neuromuscular blocking agents promote insufficient ventilatory response to hypoxia and regurgitation/aspiration. As a result, the incidence of pulmonary complications have been found to be higher in both early and late postoperative period in patients with residual curarisation. Clinical tests such as the head lift test and visual or tactile evaluation of the response to peripheral nerve stimulation are no longer sufficient to exclude postoperative residual curarisation. Residual curarisation is still present at the time of extubation despite the use of subject if monitoring of neuromuscular function, clinical tests and/or reversal of neuromuscular blocking agents. In contrast, acceleromyographic monitoring provides a valuable tool to avoid residual curarisation and to reduce the related-side effects.