Objective To study the effects of patient-controlled intravenous analgesia (PCIA) on plasma endothelin-1 (ET-1) of patients after mitral valve replacement.Methods One hundred and twenty ASA Ⅱ -Ⅲ patients undergoing mitral valve replacement were randomly divided into four groups, 30 cases in each group. The patients were given PC IA with lornoxicam 16 μ g/(kg·h ) in group L, fentanyl 0.2 μ g/( kg·h) in group F, tramadol 0.2 mg/(kg·h) in group T,and without PCIA in group D. VAS score and Ramsay score were recorded at 8,12,24 and 48 h after operation.The plasma ET-1 levels were detected using radioimmunoassay before anesthesia induction,at 8,12 and 24 h after operation.Results VAS scores in group L, F,T were lower at 8,12 h after operation than those in group D,Ramsay scores in group L, D were lower than those in group F,T.ET-1 levels in group L,F and T were significantly lower than those in group D at 8,12 and 24 h after operation (P <0.05).The numbers of dizziness, nausea,vomiting after operation in group L[3.3%(1/30) ,3.3%( 1/30),0]and group D(0)were significantly less than those in group F[13.3% (4/13), 13.3%(4/13), 10.0%(3/30)]and group T[10.0%(3/30), 26.7%(8/30), 16.7%(5/30)](P < 0.05).Conclusion PCIA with lornoxicam is a better method of suppressing the increase of plasma ET-1 levels with less side effects in the patients after mitral valve replacement.