PURPOSE: To investigate the influence of age on the neuromuscular blocking effect of cisatracurium. METHODS: 90 patients with ASA I and II were assigned to the following groups according to their age: adults, children, and infants. Each group was subdivided into three subgroups according to the first dose of cisatracurium. Patients were administrated at a first dose of cisatracurium randomly, and their responses to train-of-four (TOF) stimulation were observed. When the same degree of the first response (T1) continuously repeats three times, the percentage of T1 inhibition was recorded, and the curve of dose-effect relationship and ED95 were calculated. A second dose of cisatracurium was then administrated (total volume 100 μg/kg). The recovery phase in each patient was observed upon T1 reaching the maximum blocking effect (100%). RESULTS: Once the maximum blocking effect was reached, patients were intubated. There were 83 cases (92.2%) of patients with grade 1 and 7 (7.8%) patients with grade 2 intubating conditions. ED95 was 59.29, 55.88 and 45.39 μg/kg in adults, children, and infants, respectively. ED95 positively correlated with age. The clinical duration of neuromuscular blockade, effective action duration of neuromuscular blockade, and in vivo action duration of neuromuscular blockade in adults was longer than that in children (P<0.05), but shorter than in infants (P<0.05). However, there were no significant differences in the recovery index among groups (P>0.05). CONCLUSION: Age influences the neuromuscular blocking effects of cisatracurium to a certain extent.