Transport proteins have essential functions in the uptake of neurotransmitters and neuromodulators. We have mapped the gene encoding the taurine transporter, Taut, to the central region of mouse chromosome 6. Analysis of a cross segregating the neurological mutant mnd2 excluded Taut as a candidate gene for this closely linked mutation. To map the human taurine transporter gene, TAUT, a sequence-tagged site (STS) corresponding to the 3' untranslated region of the human cDNA was developed. TAUT was assigned to human chromosome 3 by typing this STS on a panel of somatic cell hybrids. Further analysis of a hybrid panel containing defined deletions of chromosome 3 suggested that TAUT maps to 3p21-p25. These data extend a conserved linkage group on mouse chromosome 6 and human chromosome 3p. Deletion of TAUT might contribute to some phenotypic features of the 3p- syndrome.