Objective To examine the hemodynamic patterns of critically ill patients with septicemia to evaluate their relationship to blood bacteriology. Design Retrospective study. Setting Medical ICUs of a tertiary care medical center. Patients Total of 59 critically ill patients with bacteremia: 33 with Gram-positive and 26 with Gram-negative bacteremia. Measurements Hemodynamic variables and mixed venous oxygen saturation (SMo2) measurements associated with the highest cardiac index measured within 72 hrs of positive blood cultures. Main Results No significant differences in cardiac index, mean arterial pressure, systemic vascular resistance, oxygen extraction ratio, or SMo2 were observed comparing the two groups. Conclusion We were unable to demonstrate clinically important differences between the hemodynamic responses to Gram-positive vs. Gram-negative sepsis.