By using particle electrophoresis and quantitative analysis the interaction of anionic surfactants (sodium dodecylculfate, sodium decylbenzene sulfonate) with a hydrocarbon-grown yeast and a commercial baker's yeast has been investigated to obtain further informations about the chemiczl composition of the surface region (3-6 nm) of the cell wall of this yeasts. A correlation is found between the chemical composition and the different adsorption behaviour of various batches of the same yeasts. It was found that surface-localized hydrophobic glycoproteins, probably proteophosphomannan are responsible for the strong p H dependent adsorption behaviour of a typical Candida species. I n contrast the cell surface of a typical Saccharomyces species was strongly hydrophilic and showed no surfactant adsorption. This can be explained by the presence of a polysaccharide probably phospliomsnnan in the surface region only. The implication of proteins in the adsorption process is confirmed by model experiments too. The models for the yeast cell mall proposed by LAXPEN and KIDBY e t al. were critically discussed in terms of our results.