This study is aimed to evaluate the improvement of the cardiac output after surgery and the side effects of dobutamin on some hemodynamic index of patients after heart valve replacement. Heart rate after 1 hour transmission of dobutamin is 101.56 +/- 17.54 beats per minute (bpm) in comparision with no dobutamin at 81.91 +/- 13.14 bpm (p 0.05), cardiac index (CI) is increased to 2.83 +/- 0.51 (1/min/m2). After 6 hours of transmission the heart rate increases to 112.50 +/- 18.17 bpm in comparison with no dobutamin at 81.91 +/- 13.14 bpm (p 0.05), cardiac output is increased to 4.38 +/- 0.42 (1/min/m2) in comparison with 2.72 +/- 0.55 (l/min/m2) before using dobutamin (p 0.05), cardiac index after 6 hours is 3.08 +/- 0.27 (1/min/m2) versus before using dobutamin 1.90 :t 0.29 (1/min/m2) (p 0.05). Stroke volume (SV) is increased by 42.29 :t 10.52 ml versus before using dobutamin 34.59 :t 8.31 ml (p 0.05). Dobutamin improves significantly stroke volume, cardiac output, cardiac index, decreases in lung and system resistance after using 1 hour. There is a statistically significance increase of the heart rate immediately and with continous use of dobutamin until discontinuation.