Acute renal failure after exercise with frank pain and patchy renal vasoconstriction is a clinical syndrome that occurs in young, previously healthy persons. The authors describe a 24-year-old man who had this syndrome. CT scan showed wedge-shaped contrast enhancement of both kidneys, which suggested patchy renal vasoconstriction. Tc-99m MDP imaging revealed diffuse increased uptake of both kidneys. After renal function was improved, Tc-99m MDP imaging showed normal uptake of both kidneys. Acute renal failure due to acute tubular necrosis was confirmed by renal biopsy. The authors conclude that Tc-99m MDP may be useful in evaluation of acute renal failure after exercise with flank pain and patchy renal vasoconstriction due to acute tubular necrosis.