The kidney plays a fundamental role in the maintenance of the homeostasis of all body fluids; it operates as an efficient buffer system in the prevention of dehydration, hyperhydration, acid base and electrolyte imbalance and it removes toxic metabolites. It is not surprising, therefore, that post traumatic acute tubular necrosis (ATN) is characterized by a mortality that exceeds 80% in spite of the progress offered by dialysis and clinical nutrition. The mechanisms of this critical pathological condition are summarized in Figure 1.