We report the isolation and characterization of an adenine-repressible gene, rds1, in the fission yeast Schizosaccharomyces pombe. The transcript of rds1 is greatly increased in abundance when adenine auxotrophic strains are starved for adenine. rds1 is also derepressed when wild-type cells are starved for glucose, ammonium, or phosphate. In addition, derepression occurs when wild-type cells are exposed to a carbon dioxide atmosphere, when they are shifted to higher temperatures or when they enter stationary phase. The nucleotide sequence of the rds1 gene and the corresponding amino acid sequence of its protein share no obvious homologies with any other known gene or protein and we have not found a phenotype for rds1 disruption mutants. We speculate that expression of the rds1 gene is regulated by one or several components of the adenine nucleotide pool and that its gene product has a function in stress-related responses of the cell.