Microcorrosion casts of the renal vascular system of tadpoles of the Clawed Frog, Xenopus laevis, were observed by scanning electron microscopy. Glomerular differentiation was studied qualitatively and quantitatively during developmental stages 56-66 (metamorphic climax). The general structure of the renal vascular system corresponds to the pattern commonly found in anurans; however, the arterial supply has conspicuous connecting vessels that supply groups of glomeruli. In the dorsal part of the kidney, qualitative differentiation of glomerular structures precedes quantitative growth. The ventral part of the kidney has larger, well-developed renal corpuscles of nearly adult appearance. Four developmental stages of glomerulogenesis are distinguished morphologically and their glomerular and vascular growth is analyzed.