THE INTRAVENOUS ADMINISTRATION of hypertonic urea solution has been advocated by Stamey in the diagnosis of unilateral renal disease by differential renal function studies. Its purpose is to promote maximal relative reabsorption of water in the ischmic kidney, and it also serves as an osmotic diuretic to assure satisfactory flow rates for the procedure. However, an additional effect of the infusion of urea solution is the decrease in cellular volume. When this occurs in the brain, intracranial hemorrhage may be precipitated. Report of a Case A 54-year-old male with known hypertension of many years duration, suffered a cerebrovascular accident in 1954 with resultant right hemiparesis. His hypertension was unsatisfactorily controlled by medical therapy. Physical examination revealed a blood pressure of 230/120 mm. Hg and a right hemiparesis marked by muscle atrophy and spasticity of the extremities on that side. A positive Babinski sign was noted on the right side. The