Sulfur dioxide tolerance of S.cerevisiae W3 and its meiotic progenies was correlated with the mobility of a particular chromosome in PFGE. Hybridization of PHO 9 DNA probe to Southern blots of the separated chromosomes revealed that chromosome XVI was the target one.Strain W 3 was observed to have two polymorphic chromosome XVI migrating with slight difference in the gel.Its longer chromosome was carried by the sulfur dioxide tolerant haploid progenies and its shorter one by the sulfur dioxide sensitive haploid progenies, respectively.The band of shorter chromosome XVI was overlapped with a chromosome, probably chromosome XIII, in the gel.