Renal and splanchnic sympathetic nerve discharge (SND) responses to heating are significantly reduced in senescent compared with young Fischer (F344) rats (Kenney and Fels, Am J Physiol Regulatory Integrative Comp Physiol, 2002). However, the functional significance of this finding is not known. We tested the hypothesis that blood flow distribution profiles to heating are altered in senescent (24-month-old) compared with mature (12-month-old) and young (3-month-old) F344 rats. Visceral organ, skeletal muscle, and tail blood flows were determined; using the radionuclide tagged microsphere technique, before (Control, 38°C) and during heating that increased body temperature (Tc) to 41°C in anesthetized F344 rats. Vascular conductance in the kidney, stomach, large intestine, pancreas, spleen, and tail was significantly reduced during control before heating in senescent compared with young F344 rats. Heating significantly decreased kidney, stomach, small and large intestine, and pancreas vascular conductance in young and mature but not senescent F344 rats. Vascular conductance at 41°C in the kidney and small intestine was significantly lower and in the stomach tended to be lower in young compared with senescent rats. Splenic conductance increased during heating in young and senescent rats but was highest in the young rats. Tail conductance during heating was significantly increased in young rats but remained unchanged in mature and senescent rats. These results demonstrate a marked attenuation in heating-induced vascular conductance changes in senescent rats, suggesting an important functional consequence for the attenuated SND responses to heating in aged rats.