Study objectives: To assess the hemodynamic changes under fluid challenges in septic shock patients evaluated by transpulmonary thermodilution of PiCCO monitoring system. Design: the observational clinical trial. with comparison. Intervention: Typical 30 ml/kg body weight crystal fluid challenges. Mesurements and results: hemodynamic parameters were evaluated by transpulmonary thermodilution of PiCCO system. Volume loading induced a significant increase (p 0,05) in GEDV index from 574 + or - 120 to 681 + or - 73 ml/m2 in cardiac index from 4,4 + or - 1,1 to 5,1 + or - 1,0 l/min/m2 and SVI from 29 + or - 5 ml/m2 to 36 + or - 4 ml/m2. The preinfusion GEDV index was lower in case of positive response, and was negatively correlated with percentage increase in GEDV index. CVP level was not correlated with increase in cardiac output and stroke volume index. Conclusion: in patients with septic shock, the findings temporarily demonstrate that PiCCO system can be used to evaluate preload (GEDVI), CI, SVRI to guide the fluid control, using inotrope and vasopressors.