More attention is being given to the essential trace elements in human nutrition, although there is much to be learned concerning requirements, function, and interactions. The extensive use of total parenteral nutrition (TPN) provides an opportunity for further study. To date, little attention has been paid to selenium (Se), an element for which both a deficiency and toxic state can exist. In a program to evaluate the effects of long-term TPN on Se nutriture, a avriety of solutions used in TPN have been analyzed. Se was not present in detectable levels in the following solutions: sodium acetate, Freamine II, NaCl, potassium phosphate, KCl, Folvite, Liquaemin Na, CaCl2, MgSO4, and NaHCO3. The solutions containing significant amounts of Se were: 50% dextrose 0.27 +/- 0.04 microgram/ml and 20% dextrose 0.27 +/- 0.08 microgram/ml (Travenol Laboratories); 50% dextrose 0.47 +/- 0.10 microgram/ml and 20% dextrose 0.35 +/- 0.07 microgram/ml (Abbott Laboratories); and 70% dextrose 0.33 +/- 0.08 microgram/ml (McGaw Laboratories). These data suggest that 200 to 400 microgram Se would be provided in the usual amounts of solution administered to an adult patient.