We have completely sequenced on both strands a continuous DNA segment of 36.2 kb located on the left arm of Saccharomyces cerevisiae chromosome XI. Sequence analysis reveals the presence of 20 open reading frames (ORFs) at least 100 amino acids long. Five of these ORFs correspond to known genes; five others show homology with known proteins; the ten remaining ORFs identified show no detectable homology with other protein sequences contained in data banks and may represent new biological functions.