A mouse lactate dehydrogenase-A (LDH-A) cDNA clone was isolated from a tesits cDNS library and its sequence of 1713 nucleotides determined. The sizes of LDH-A mRNAs from mouse testis and liver were shown to be 1.7 an d1.6 kilobases, respectively. A comparison of this LDH-A cDNA sequence with the previously-reported genomic sequence of mouse LDH-A cDNA gene (KM Fukasawa and SS-L Li, Genetics 116, 99-105, 1987) revealed that testicular and somatic LDH-A mRNAs differ only in their distinct 5´ non-coding exons of 174 and 78 nucleotides, respectively. (J Gent Mol Biol 1990; 1: 1-6)