A genetic system for the analysis of antisense and ribozyme mechanisms is a much needed experimental tool, and yeast represent a favorable organism on which to base such a system. We have shown previously that the fission yeastSchizosaccharomyces pombehas potential to satisfy the requirements of such a system. This report describes experiments designed to determine if antisense and ribozyme RNA-mediated gene suppression will be generally applicable to other genes inS. pombe. Antisense and ribozyme RNAs designed to suppress theade6gene were expressed at high levels from episomal expression vectors. Theade6gene was chosen as a target as mutations within the gene confer adenine auxotrophy and a red colony phenotype, and it was expected that antisense or ribozyme RNA-mediated mutant phenocopies would exhibit the same readily detectable phenotype. No phenotypic indication ofade6suppression was detected in transformed yeast, andade6target mRNA was analyzed by primer extension and Northern analysis. Initially, conflicting results were obtained from these techniques, which were determined to be due to duplex formation between antisense and target RNAin vitro. No detectable reduction in theade6mRNA levels was found, and it was concluded that the gene was not suppressed by the antisense or ribozyme RNAs tested. These results confirm that inS. pombeas with other organisms, the susceptibility of genes to RNA-mediated suppression may be gene specific and that design of antisense and ribozyme genes will be an empirical process.