Saccharomyces cerevisiae (CCT(-)3174 and commercial baker＇s yeast) was immobilized by adsorption onto chrysotile. The adsorbed yeast cells were easily washed out, but cells grown in situ were strongly attached by entrapment by chrysotile microfibres. In fermentation experiments with 30% (w/v) glucose solution, the immobilized cells showed a 1.3-fold increase in initial reaction velocity. For immobilized CCT 3174, the final ethanol yield was 26% higher than that with free cells.