Objective To evaluate the accuracy of target-controlled infusion (TCI) of sufentanil from termination of cardiopulmonary bypass (CPB) until the end of surgery in the patients undergoing cardiac surgery.Methods Twenty adult patients,aged 25-64 yr,of ASA physical status Ⅱ or Ⅲ,scheduled for elective coronary artery bypass graft under CPB,were enrolled in the study.Immediately after termination of CPB,sufentanil was given by TCI using Gepts pharmacokinetic parameters.The initial target effect-site concentration (Ce) of sufentanil was 0.4 ng/ml.The Ce increased by 0.2 ng/ml every 10 min until it finally decreased to 0.8 ng/ml,and then the Ce decreased by 0.2 ng/ml every 10 min until it finally decreased to 0.4 ng/ml which was maintained until the end of surgery.At 10 min of infusion at each preset target Ce 0.4,0.6,0.8 and 0.6 ng/ml (T1-4) and 1,3,5,10,20,40 and 60 min of infusion at the last concentration of 0.4 ng/ml (T5-11),arterial blood samples were collected for measurement of sufentanil concentrations by using ELISA.For each sample,the bias,accuracy and wobble were calculated.Results Compared with the predicted plasma concentrations of sufentanil,the measured plasma concentrations of sufentanil were significantly decreased at T1-11.The bias,accuracy and wobble were-37.63 ％,37.63％ and 5.09％,respectively.Conclusion The accuracy of sufentanil TCI using Gepts pharmacokinetic parameters is not high from termination of CPB until the end of surgery in the patients undergoing cardiac surgery.