Hyperphosphatemia is an electrolyte abnormality that most frequently results from renal insufficiency and the attendant inability to excrete phosphorus (PO4) efficiently. A case is presented in which a young man with hemorrhagic shock developed severe hyperphosphatemia in the absence of renal failure. This is the first such case documented to the authors' knowledge. The prompt correction of the primary cause (ie, hypoperfusion and acidosis) resulted in a rapid return of PO4 levels to normal. This was probably related to the intracellular shift of PO4. Physicians should be aware of this electrolyte disturbance because it is not a well-recognized complication and because, in most cases, proper treatment of shock will also correct the elevated PO4.