A 6-yr-old girl who lost 300 cm of intestine was maintained by total parenteral nutrition. After 5 months on a preparation rich in linoleic acid but low in linolenic acid she experienced episodes of numbness, paresthesia, weakness, inability to walk, pain in the legs, and blurring of vision. Diagnostic analysis of fatty acids of serum lipids revealed marginal linoleate deficiency and significant deficiency of linolenate. When the regimen was changed to emulsion containing linolenic acid neurological symptoms disappeared. Analysis indicated that linoleate deficiency had worsened but linolenate deficiency had been corrected. The requirement for linolenic acid is estimated to be about 0.54% of calories.