The PDGFbr gene has been implicated in many physiological processes including development and wound healing. Aberrant expression of the receptor is seen in many pathological conditions such as atherosclerosis and inflammatory diseases. To study the mechanisms of PDGFbr regulation, we identified the regulatory regions of the gene. We have cloned and characterized the promoter region of the plateletderived growth factor beta receptor (PDGFbr). We isolated a 4.5 Kb genomic fragment which confers PDGFbr tissue-specific promoter activity. This fragment can direct transcription of a luciferase reporter gene in a cell-specific manner which correlates well with the known pattern of expression of the PDGFbr. The specificity of this clone was demonstrated by its high activity in NIH 3T3 fibroblasts and lack of activity in N-MUNG epithelial cells, a pattern that parallels the expression of the endogenous PDGFbr. We have defined a 614 bp region encompassing the 58 untranslated region of the gene which includes the basal promoter region. We generated transgenic mice that carry the chloramphenicol acetyltransferase (CAT) reporter gene under the control of the 4.5 Kb promoter. The expression pattern of the reporter gene was compared to that of the endogenous PDGFbr gene. The promoter was able to direct reporter gene expression with the same temporal and spatial pattern as the endogenous PDGFbr. The most prominent expression was in condensing mesenchyme of developing blood vessels, bone and tissues adjacent to epithelium. We conclude that this clone contains the regulatory regions sufficient to direct expression of the PDGFbr. The further analysis of this promoter will help elucidate the transcriptional regulation of expression of the PDGFbr, and provide a useful tool for directing expression of heterologous genes.