The two genes encoding thioredoxins in Saccharomyces cerevisiae, TRX1 and TRX2, map to chromosome XII and VII, respectively. From the DNA sequence of the intragenic region TRX1 is 500 bp downstream of PDC1. Tetrad analysis places TRX2 1.1 cM from ADE3, while a physical map of this region positions TRX2 4.5 kb downstream of ADE3. The mapping of TRX1 adjacent to PDC1 clarifies previous results (Muller, E. G. D. J. Biol. Chem. 266, 9194-9202, 1991) that suggested a third thioredoxin gene.