Dmrt1 gene is the first sex differentiation gene found conserved across animal phyla. It plays an important role in mammalian sexual differentiation. Sequence analysis of mammalian dmrt1 5' and 3' flanking regions showed that there were three and seven conserved regions (>60% homology), respectively. Dmrt1 promoter, 3' flanking region and coding sequence were amplified, cloned into expression vectors and transfected into both COS-7 and ST cells. Results indicated that both 5' and 3' flanking sequences could direct the expression of reporter gene gfp and dmrt1. However there was clearly a difference in expression efficiency between different cells. These results indicated that regulation of dmrt1 expression may be cell-specific and complex regulatory mechanism may be involved in dmrt1 expression.