The transcriptional control elements of tissue-specific genes may be exploited in the design of therapeutic constructs for use in human gene therapy. The uroplakins are a family of four proteins which form the asymmetric unit membrane of the urothelium. We have cloned the human uroplakin Ia gene and defined its genomic structure and transcriptional start site. Using quantitative RT-PCR in an extended panel of normal tissues, we have demonstrated highly urothelial-specific expression of this gene. A Dual-Luciferase assay was used to assess the transcriptional activity of a variety of promoter fragments of the human uroplakin Ia gene. A highly specific promoter fragment (consisting of 2147 bp of 5'-flanking sequence, intron 1 and the 5' UTR) was identified which regulated urothelial-specific expression in vitro. The human uroplakin Ia promoter identified has potential use in future gene therapy strategies to restrict transgene expression to the urothelium.