The Saccharomyces cerevisiae genome contains many duplicated regions of DNA. The presence of extra copies of some genes can result in certain genes performing similar or identical functions as their duplicated counterparts. This study reveals phenotypes for functionally overlapping genes and classifies selected duplicated genes as functionally overlapping or divergent.  A region of DNA on chromosomes I and XV containing 12 duplicated genes was examined. Mutants were created containing deletions of one or both members of every gene pair and subjected to several functional tests. Gene pairs were classified as functionally overlapping when both members had to be deleted to observe a "synthetic" phenotype. Gene pairs were considered to be functionally divergent when the removal of one member of a gene pair revealed a mutant phenotype, as the remaining member was unable to "rescue" the phenotype.