The effects of halothane on renal hemodynamics under both normovolemic and hypovolemic conditions were investigated in chronically instrumented conscious dogs whose homeostatic mechanisms were not altered by the presence of preexisting drugs. Renal blood flow and aortic pressure were assessed by prior implantation of Doppler ultrasonic flow probes on the renal artery and a catheter in the descending aorta. Administration of halothane to conscious normovolemic dogs (Group HN) resulted in 11–26% decreases in renal vascular resistance with no significant changes occurring in renal blood flow. In a second group of animals made hypovolemic while awake (Group AH), 30% of the blood volume was removed over one-half hour. In response to hemorrhage, these conscious animals' renal blood flow did not significantly change from the normovolemic control, and renal vascular resistance significantly decreased. With no further intervention, renal vascular resistance and renal blood flow remained unchanged from the level achieved after the 30% hemorrhage. A third group of animals (Group HH) was hemorrhaged in a manner similar to that of Group AH. They also showed no significant changes in renal blood flow and a significant decrease in renal vascular resistance in response to hemorrhage. Thereafter, administration of halothane, as in Group HN, to this group produced 11–23% decreases in renal vascular resistance with no significant decline in renal blood flow from the hypovolemic control levels established after hemorrhage. The author concludes the following: 1) administration of halothane to normovolemic conscious dogs does not decrease renal blood flow; 2) a moderate degree of acute hemorrhagic hypovolemia does not decrease renal blood flow in conscious dogs; and 3) administration of halothane to acutely hypovolemic conscious dogs does not impair renal perfusion.