OBJECTIVE To explore the neuromuscular effects of cisatracurium besylate in morbidly obese patients when dosed according to real body weight under total intravenous anesthesia with propofol. METHODS Thirty-six ASA I-II patients aged 18-65 years scheduled for elective procedures at our hospital during July 2012 to December 2012 were allocated into 2 groups according to body mass index (normal weight: body mass index: <24, overweight: body mass index >28). Anesthesia was induced with target-controlled infusion of propofol (Cp 3 µg/ml) and remifentanil (Ce 3-5 ng/ml). A bolus of cisatracurium 0.2 mg/kg was administered intravenously over 5-10 s as soon as a patient lost consciousness. Neuromuscular block was monitored with TOF-Watch SX (Oaganon, the Netherlands). Single stimulation (0.1 Hz) was applied to ulnar nerve at wrist. The maximal degree of neuromuscular block, onset time, clinical duration and recovery index were recorded. They were intubated and mechanically ventilated when neuromuscular block reached the maximal degree. The intubation condition was evaluated. RESULTS The average onset time was (164 ± 25) s in obese group versus (201 ± 48) s in normal weight group. And there was significant difference between groups (t = 2.83, P < 0.05) . The clinical duration was (68.4 ± 9.6) min in obese group versus (62.0 ± 6.5) min in normal weight group. And there was significant difference between groups (t = 2.33, P < 0.05). The recovery index was (15.6 ± 4.7) min in obese group versus (10.8 ± 4.2) min in normal weight group. And there was significant difference between groups (t = 3.03, P < 0.05) . Also 75% recovery time was (83.9 ± 11.5) min in obese group versus (73.0 ± 9.2) min in normal weight group. And there was significant difference between groups (t = 2.94, P < 0.05). But no differences existed in intubation conditions. CONCLUSIONS When dosed according to real body weight, onset time of cisatracurium is shorter while clinical duration and recovery index are prolonged in morbidly obese patients compared with normal weight counterparts.