Objective To compare the effects of different doses of propofol on cardiac pump function in morbidly obese patients. Methods Forty morbidly obese patients undergoing laparoscopic Roux-en-Y gastric by-pass were randomly divided into lean body weight(LBW)group and total body weight(TBW)group,with 20 cases in each group.In LBW group,patients were induced by propofol with a dose according to LBW(kg)×2.0 mg/kg but in TBW group,patients were induced by propofol depending on TBW of the patients.We monitored the changes of left ventricular ejection fraction(LVEF)and stroke volume(SV)in patients before anesthetic induction(T1)and at 1 min(T2)after propofol administration.At the same time,we monitored invasive arterial pressure,noninvasive arterial pressure,BIS,and SpO2.Results Compared with those measured at T1,LVEF and SV were decreased af-ter the induction of anesthesia in the 2 groups(P < 0.05);compared with LBW,TBW had greater influence on LVEF and SV after the induction of anesthesia(P<0.05);compared with those at T1,non invasive arterial blood pressure,invasive arterial blood pressure and mean arterial pressure decreased after theinduction of anesthesia (P<0.05);compared with LBW,TBW had no significant effect on noninvasive arterial blood pressure,invasive arterial blood pressure and mean arterial pressure after the induction of anesthesia(P < 0.05);BIS was less than 50 after the induction of anesthesia in 2 groups. Conclusion Propofol induction with a LBW-dependent dose has less influence on cardiac pump function in morbidly obese patients while ensuring the depth of anesthesia.