N-acetyl-DL-tryptophan is produced (1) by room temperature condensation of DL-serine and indole in the presence of acetic acid and acetic anhydride at 62% yield. A part of-the unreacted indole is easily extracted with ether and recycled. The overall conversion of indole is 85%. The DL-serine is the product of a method developed in Snamprogetti laboratories (2). The acetyl-DL-tryptophan in turn is asymmetrically hydrolyzed by acylase entrapped in cellulose triacetate fibers to produce L-tryptophan and acetyl-D-tryptophan.