1. Infusion of contrast material in the range of 1 ml. per pound of body weight results in total body opacification in the adult. 2. Structures of the body will opacify to a degree proportional to their vascularity and the amount of contrast material in their extracellular spaces. In this way, adjacent structures of persistent water density may be separated. 3. Cystic, necrotic, and hypovascular lesions within vascular organs may be demonstrated by this technique.