This study was carried out to compare cardiac output measurement determined by thermodilution with Swan - Ganz catheterization versus left ventricular outflow tract Doppler echocardiography in septic shock patients. Sixty one assessments were performed on twenty patients. There was a statistically significant correlation between the left ventricular outflow tract Doppler echocardiography and thermodilution technique for assessment of cardiac output (r = 0,99, P 0.01). In conclusion, there was a good correlation between the cardiac output measurement determined by left ventricular outflow tract Doppler echocardiographic technique and by thermodilution using catheter Swan - Ganz in septic shock patients.