We studied hemodynamic and renal effects of increasing the dosage of dopamine (DP) by 5 μg/kg·min, in 7 patients with peritonitis and clinical findings of septic shock, all of whom were already receiving variable dosages of DP. Stroke index (SI) (p<. 01), except in 3 cases, and mean arterial pressure (p< .01) were significantly elevated without significant increases in HR and systemic vascular resistance index (SVRI). Changes in mean pulmonary artery pressure (MPAP) and pulmonary wedge pressure (WP) were insignificant (<3 mm Hg). Renal response showed augmentation of diuresis (p< .01), inulin clearance (Cin) (p< .05), and fractional excretion of sodium (FENa) (p= .02) without significant changes in either paraminohypurate clearance (Cpha) or filtration fraction. There was no correlation between hemodynamic or renal changes and initial dosage of DP. We conclude that increasing the DP dosage in septic shock patients may be useful even when the patient is already receiving large doses. Increased natriuresis was not due to changes in plasma renal flow.