AbstractSix open reading frames (ORFs) of unknown function from Saccharomyces cerevisiae from the left arms of chromosomes VII and XV were disrupted by the short‐flanking homology method in the diploid strains FY1679 and CENPK2. In each case, the entire ORF, with the exception of the first nucleotide of the start codon, was eliminated and replaced by the kanMX4 cassette. Correct integration of the disrupting marker was checked by colony PCR of the geneticin (G418)‐resistant transformants. Sporulation followed by tetrad dissection of the diploids revealed that none of the ORFs encoded a product essential for the viability of either yeast strain. The neutral effect of these disruptions extended to mating and sporulation, since it was possible to create homozygous diploid disruptants that were capable of sporulation. Basic phenotypic analysis was carried out on all strains by growing them on three different media at three different temperatures and revealed no significant differences between disruptants and the parental strains. A cognate clone and a kanMX4 disruption cassette were created for five of the six ORFs by gap repair with specific long‐flanking homology cassettes. For experimental reasons, the cognate clone and disruption cassette corresponding to the sixth ORF (YGL161w) had to be created by PCR. Copyright © 2002 John Wiley & Sons, Ltd.