Objective: The aim of the study was to investigate the incidence of postoperative residual curarization (PORC) after rocuronium administration using normalized acceleromyographic (AMG) train-of-four (TOF) ratios. Material and Methods: During propofol-fentanyl-nitrous oxide anesthesia, neuromuscular block was monitored using acceleromyography method in 130 patients. A TOF ratio measured at the end of control stimulation was recorded as a baseline TOF value. Neuromuscular block was induced with rocuronium 0.6 mg.kg(-1) and antagonized with neostigmine 40 mu g.kg(-1) at the end of anesthesia. Immediately after the patients' arrival in the postanesthetic care unit (PACU), TOF ratios were measured and normalized (i.e., dividing the raw TOF ratio by the baseline TOF value). The incidences of PORC were determined according to three different TOF threshold values: Normalized AMG-TOF ratio <1; raw AMG-TOF ratio <1; and raw AMG-TOF ratio <0.9. Results: The baseline AMG TOP ratios varied widely 110.8 (91-149) among patients. Considering normalized AMG-TOF ratios <1 as PORC, 77(63.1%) patients had PORC on arrival to the PACU. Significantly fewer patients had raw TOF ratios < 0.9(39 subjects, 31.9%), and <1(67 subjects, 54.9%) than whose normalized TOF ratios <1(77 subjects, 63.1 %) (p<0.05). Although not statistically significant, the when it was determined using normalized AMG-TOF ratios rather than using raw AMG-TOF ratios (18.3% and 10%, respectively). Conclusion: Despite reversal of neuromuscular block with neostigmine, the incidence of PORC is very high after rocuronium administration.