The effectiveness and safety of iv infused norepinephrine (0.5 to 1 microgram/kg X min) were evaluated in 12 hyperdynamic vasodilated septic patients, who remained hypotensive despite iv volume expansion and antimicrobial and dopamine therapy. During norepinephrine infusion, mean arterial pressure and systemic vascular resistance index increased (p less than .001) and heart rate decreased (p less than .02). Cardiac index either increased or was unchanged in ten patients and decreased slightly in the remaining two patients. Urine flow increased (p less than .01) and was more than 0.5 ml/min when a critical renal perfusion pressure was reached if renal damage was not overwhelming. We conclude that norepinephrine may improve arterial BP and urine flow when volume replacement and dopamine therapy have failed to reverse the hypotension of septic shock.