Non-covalently attached or soluble cell wall proteins of Saccharomyces cerevisiae were extracted using a high pH/2-mercaptoethanol procedure and were separated for peptide sequencing using 2D-PAGE. A partial N- terminal sequence of a major protein spot was obtained and showed high identity with enolase gene products. Western blotting with an anti-enolase antibody confirmed that enolase was present in the cell wall extract. Biotinylation of cells prior to protein extraction with a membrane impermeable biotinylating agent confirmed that the detection was not owing to cell lysis during extraction. Transmission immunoelectron microscopy showed enolase to be present in the cell wall. Enolase contains no known secretion signal that would localize it to the cell wall. Thus S. cerevisiae must have further mechanisms for targeting proteins to the cell wall.