After restoring plasma volume to conscious levels, glomerular pressures and flows governing single nephron glomerular filtration rate (SNGFR) were measured in Munich-Wistar rats possessing surface glomeruli accessible to micropuncture. Although the mean glomerular transcapillary hydraulic pressure difference in these euvolemic rats was similar to that observed in hydropenic animals, initial glomerular plasma flow rate and SNGFR were at least 50% higher than in hydropenic rats. Nevertheless, filtration pressure equilibrium was generally achieved in euvolemic rats, as in hydropenic rats. Afferent and efferent arteriolar resistances were found to be lower in euvolemic than hydropenic rats, suggesting more potent vasoconstrictor forces in the latter group.