A twelve year old boy presented with sudden onset of severe hypertension and oligo-anuria. A diagnosis of Takayasu's Arteritis was made by aortography which demonstrated irregular narrowing of the lumbar aorta and renal arteries. Severe renal insufficiency necessitated maintenance hemodialysis. Hyperreninemic hypertension was intractable despite aggressive dialysis and multiple drug therapy. Renal biopsy after eight months of dialysis showed preservation of glomerular architecture. After nine months GFR improved spontaneously to 32 ml/min/1.73 m2 despite no improvement in his hypertension. This case report emphasizes the remarkable ability of renal parenchyma to recover function after sustained ischemia.