Chinese hamster X mouse hybrid cells segregating mouse chromosomes have been used to assign a gene for triosephosphate isomerase (TPI-1, EC 5.3.1.1, McKusick No. 19045) to mouse chromosome 6, and a gene for Glyoxalase-I (GLO-1, EC 4.4.1.5, McKusick No 13875) to mouse chromosome 17. The genes for TPI-1 and lactate dehydrogenase B are syntenic in man and probably so in the dog. It is therefore likely that they are syntenic also in the mouse. It is of interest then that there is a mouse gene, Ldr-1, on chromosome 6 that regulates the level of LDH B subunits in mouse erythrocytes. The locus for GLO-1 is closely linked to the major histocompatibility complex in man. Since the major histocompatibility complex in the mouse is present on chromosome 17, this locus and the Glo-1 locus are syntenic in the mouse as well. This finding adds to the number of autosomal gene pairs which are syntenic in both mouse and man and reinforces the belief that there is considerable conservation. of linkage groups during evolution.