Twenty-seven infants from 1 day to 9 months of age with severe intractable diarrhea were fed an oral elemental diet (Vivonex) consisting of crystalline amino acids, glucose, electrolytes, and vitamins by continuous nasogastric drip. Complete control of diarrhea was achieved in 24 patients (89 percent) who had an average weight gain of 28 gm/day. Nitrogen balance and plasma amino acids were measured in five patients while they received 2.25 gm of amino acid/kd/day for two weeks and 4.58 gm of amino acid/kg/day for two weeks; the nitrogen balance and weight gain in three patients was proportional to the amino acid intake. When compared to normal levels, plasma amino acids were not appreciably increased with the lower amino acid intake. With the higher amino acid intake, there were significant increases in plasma values for 11 amino acids.