Zygosaccharomyces priorianus converted L-tryptophan to tryptophol and to small quantities of indole-3-acetic acid. Neither tryptophol nor indole-3-acetic acid was metabolized when added separately to growing cultures. The possible intermediacy of indole-3-pyruvic acid, indole-3-acetaldehyde, and tryptamine in the degradation of L-tryptophan was tested by feeding these compounds to Z. priorianus and Saccharomyces cerevisiae. Indole-3-pyruvic acid and indole-3-acetaldehyde were converted to tryptophol and indole-3-acetic acid, with the latter accumulating only in small amounts. Tryptamine was converted to its N-acetyl derivative by these organisms. A qualitative study was made on the metabolism of L-phenylalanine, L-tyrosine, and L-5-hydroxytryptophan by these organisms. Like L-tryptophan, these amino acids were metabolized to their respective alcohol and acid derivatives. Of a large number of organisms tested, the yeasts possessed the highest capacity for degrading L-tryptophan to tryptophol.