We report here the construction of six deletion mutants and the analysis of their basic phenotype. Deletion cassettes containing the KanMX4 marker module and long flanking regions homologous to the target locus were constructed for each of the six open reading-frames (ORFs YDL088c, YDL087c, YDL086w, YDL085w, YDL084w and YDL082w) located on chromosome IV. Sporulation and tetrad analysis of heterozygous deletant strains revealed that, in the FY1679 genetic background, ORFs YDL088c, YDL087c and YDL084w are essential genes for vegetative growth whereas YDL086w, YDL085w and YDL082w are non-essential. ydl088c delta and ydl084w delta haploid strains are viable in the CEN. PK2 genetic background although ydl084w delta grows at a slower rate than the wild type. Complementation tests by corresponding cognate genes confirmed that gene inactivation was responsible for these growth defects.