Abstract: The yeast deletion collection includes approximately 4,700 strains deleted for both copies of every non-essential gene. This collection is a powerful resource for identifying the cellular pathways that functionally interact with drugs. In the present study the complete pool of approximately 4,700 barcoded homozygous deletion strains of Saccharomyces cerevisiae were surveyed to identify genes/pathways interacting with 1-methyl-4-phenylpyridinium (MPP(+)) and N,N-dimethyl-4-4-bipiridinium (paraquat), neurotoxicants that can produce Parkinson's disease. Each yeast mutant is molecularly 'barcoded' the collections can be grown competitively and ranked for sensitivity by microarray hybridization. Analysis data from these screens allowed us to determine that the multivesicular body pathway is an important element of toxicity induced by both MPP(+) and paraquat. When yeast genes that when deleted showed sensitivity to MPP(+) and paraquat toxicity were analyzed for their homology to human genes 80% were found to have have highly conserved human homologs (with e<10(-8)). Future work will address if these human genes may also functionally interact with MPP(+) and paraquat toxicity.