To the Editor.—Since the reintroduction of fat emulson into the marketplace, surgeons have expressed interest in the compatibility of the product with the dextrose, amino acids, and electrolytes that comprise the balance of total parenteral nutrition regimens. Reports1 from Europe have inferred that no overt toxicity is associated with chronic infusion of admixtures containing all these elements; however, these reports lacked a component to characterize the emulsion's ability to withstand the nutrient additives over time. This is a serious consideration since studies2 with earlier intravenous (IV) emulsion products found the emulsions to cream and flocculate when admixed with salts of sodium, potassium, and calcium ions. These flocculated products were subsequently found to produce considerable adverse effects (eg, chest pressure, precordial pain, nausea, backache, and dyspnea) on IV infusion. This communication then, is intended to briefly report research undertaken to assess and predict the compatibility of the IV soybean oil