Total Parenteral Nutrition (TPN) provides i.v. daily nutrients requirements of the patient, in the form of simple compounds that normally are absorbed from digestive tract. As patients receiving TPN are seriously ill the quality and stability of TPN mixtures is of great importance. Fat emulsions are the most sensitive components of TPN mixtures. They can be modified by other components of a mixture as well as influenced by external agents like temperature and light, and oxygenation reactions. Stability of TPN mixtures, with the focus on influence of electrolytes on decomposition of fat emulsions was studied. Also the stability of newly invented compositions of TPN mixtures was examined. The study involved:visual observation, microscopic examination, pH and osmolarity measurement. The influence of phosphate, potassium, calcium, magnesium and zinc ions, in normally used concentrations in TPN on fat emulsions stability was defined and the influence of temperature, light and volume on the time in which visual and organoleptic changes appeared was estimated. Moreover, it was found that twelve TPN mixtures with suggested new compositions were stable for 7 days of storage at +4C.