The use of total nutrient admixtures (TNA) has increased dramatically in both the clinical and home care setting since 1983. The popularity of these dosage forms rests in supplying all the nutrients in one container that meets the nutritional goals of the patient. In addition, TNA formulations obviate the need for either separate peripheral venous catheters or co-infusions into the primary venous line, thus simplifying this complex therapy. Moreover, the clinical benefits derived from this practice are related to a reduction in glucose-associated complications that assume particular importance in the acutely ill patient. Although much experience has been gained over the last 12 years, practice standards vary with the institution. Despite this, TNA therapy has been successful in the U.S. This paper attempts to delineate the important physicochemical variables that influence emulsion stability as they relate to clinical practice.