Regions of the sugarcane bacilliform badnavirus genome were tested for promoter activity. The genomic region spanning nucleotides 5999–7420 was shown to possess promoter activity as exemplified by its ability to drive the expression of the coding region of the uidA gene of Escherichia coli, in both Avena sativa and Arabidopsis thaliana. In A. sativa, the promoter was active in all organs examined and, with the exception of the anthers where the expression was localized, this activity was constitutive. In A. thaliana, the promoter activity was constitutive in the rosette leaf, stem, stamen, and root and limited primarily to vascular tissue in the sepal and the silique. The transgene was inherited and active in progeny plants of both A. sativa and A. thaliana.