Three patients undergoing prolonged total parenteral nutrition at home developed skin lesions, characterized by dryness and scaly appearance, initially confined to the folds but becoming subsequently generalized. Fatty acid measurements in plasma of these patients showed a markedly abnormal lipid pattern: accumulation of 5,8,11-eicosatrienoic acid (20:3ω) and a high 20:3ω9-to-20:4ω6 ratio. When parenteral fat (Intralipid®) was administered, 500 ml/day, serial measurements of fatty acids showed a progressive normalization of the abnormal pattern and a dramatic improvement in the skin lesions. It appears that the daily requirement for linoleic acid in the adult, particularly during the period of rapid anabolism, has not been clearly established. Because more and more patients are becoming partly or totally dependent on parenteral nutrition for prolonged periods of time, the availability of parenteral fat preparations is urgently needed.