AbstractThe tissue specificity of a proposed cis‐acting temporal locus (Adh‐3t), which regulates alcohol dehydrogenase C2(ADH‐C2) activity in mouse reproductive tissue extracts, has been examined in C5 7BL/6J, SM/J, F1(SM/J × C5 7BL/6J) mice as well as in progeny of an (F1[SM/J × C5 7BL/6J] × C5 7BL/6J) back‐cross. Electrophoretic variants for ADH‐C2, previously used to localize the gene (Adh‐3) encoding this enzyme on chromosome 3, enabled the relative parental contributions to ADH‐C2phenotype in F1and backcross mouse tissues to be determined. These analyses demonstrated that (1) stomach, kidney, lung, adrenals, seminal vesicles, epididymis, uterus, and ovary ADH‐C2is encoded by a single locus (Adh‐3); Adh‐3t is differentially active in various tissues, eg, lung exhibits no apparent activity whereas the temporal locus is fully active in seminal vesicles; (3) Adh‐3t is probably differentically active in different cells of some tissues, eg, adrenals. Specific activity profiles of stomach and epididymal ADH‐C2during the neonatal development of C5 7BL/6J, SM/J, and F1(SM/J × C5 7BL/6J) male mice supported the proposal for a cis‐acting temporal locus for this enzyme. Genetic analyses examining segregation of Adh‐3 and Adh‐3t among backcross progeny suggested that these are distinct but closely linked loci, since one recombinant among 256 progeny was observed. Linkage data of Adh‐3 with Va (varitint‐waddler) and de (droopy ear) was also obtained, which suggested that Adh‐3 is loca