Adaptation to osmolarity changes is fundamental for life in unicellular organisms. A Saccharomyces cerevisiae genome array was used to analyze changes in transcriptional expression after different hypo-osmotic stresses in a wild-type strain. In the first pair of experimental conditions, cells were grown in hypotonic conditions with the presence or absence of sorbitol. In the second pair of experimental conditions, cells, with and without protection by sorbitol, were shifted from normal osmotic media to hypotonic conditions generated by dilution. Results of the two experimental sets are compared in between and with previous published data.