Plate counts on both high and low water activity (aw) media were performed during the growth of Candida utilis in batch culture. The results revealed a marked discrepancy between the counts on the two media in the logarithmic phase. The discrepancy almost disappeared in stationary phase revealing a higher resistance of these cells, as compared to growing cells, to the severe dehydration imposed by the hyperosmotic shock upon transfer to low aw medium. Since the two types of cells differ in the level of endogenous trehalose the relation between plating discrepancy and trehalose content of the cells was investigated. Treatments that changed the intracellular trehalose concentration did not modify the plate counts on low aw medium. It was therefore concluded that the amount of trehalose into the cells is not the only factor conferring resistance against the hyperosmotic shock. Glycerol content did not correlate with resistance to the water stress either. Congruent with the former conclusion, other yeast species (Sporobolomyces salmonicolor, Schizosaccharomyces pombe) showed no correlation between changes in the trehalose content and susceptibility or resistance to the osmotic stress in low aw medium.