Background: Residual muscle paralysis after anesthesia is common after pancuronium, but less common following the intermediate-acting drugs vecuronium and atracurium. Therefore, many anesthetists do not monitor neuromuscular function when using an intermediate-acting agent. The purpose of this prospective, randomised and double-blind study was to establish the incidence and degree of postoperative residual block following the use of rocuronium in patients not monitored with a nerve stimulator, and to compare it with results obtained in patients monitored using acceleromyography (AMG). Methods: During propofol/opioid anesthesia, 120 adult patients were randomised to two groups, one monitored with AMG, the other using only clinical criteria without a nerve stimulator. Postoperatively, TOF-ratio was measured with mechanomyography; a TOF-ratio <0.80 indicated residual muscle paralysis. Results: Residual muscle paralysis was found in 10 patients in the group without neuromuscular monitoring (16.7%) (95% confidence interval, 12-21%) and in two patients in the AMG-monitored group (3%) (95% CI, 0-8%); (P=0.029, Fisher's exact test). Time from end of surgery to tracheal extubation was significantly longer in the AMG-monitored group (12.5 min) than in the group not monitored with AMG (10 min). Conclusion: Clinical evaluation of recovery of neuromuscular function does not exclude significant residual paralysis following the intermediate-acting muscle relaxant rocuronium, but the problem of residual block can be minimized by use of AMG.