The administration of a single admixture of the components used in total parenteral nutrition has been considered more convenient and to give rise to less infection than the conventional regimen with separate infusions. The physico- chemical properties of several admixtures corresponding to commonly used regimens for complete parenteral nutrition have been studied. A 28 day toxicity study was carried out in the dog for one of these mixtures. It was concluded that Intralipid an be mixed with Vamin and dextrose solutions, supplemented with electrolytes, trace elements and vitamins provided that the admixtures are within certain defined ranges, prepared under strictly aseptic conditions and used within a limited time. Deviations from these ranges and component formulae should not be made without appropriate testing.