Renin, a key enzyme controlling blood pressure, is produced mainly in the kidney. To identify the transcriptional regulatory elements of the mouse Ren-1 ^c gene, the promoter regions were fused to the CAT reporter gene and transfected into embryonic kidney-derived 293 cells and four extrarenal cell lines, HeLa, HepG2, HT1080 and NIH3T3 cells. Transient transfection assay showed that sequences from – 365 to +16 of the renin gene could direct transcription of the CAT hybrid gene only in 293 cells. Deletion analysis identified two transcriptlonally active regions; the renin upstream–promoter element (RU–1 element; position –224 to –138) and the renin proximal–promoter element (RP–2 element; position –75 to –47). Although the RU–1 element functioned as an activator, depending on its orientation, it failed to trans-activate the renin promoter when the RP–2 element was deleted. By contrast, the proximal element alone exhibited a weak trans-activator property. Gel shift assay identified RU–1 element-binding factors in both 293 and HeLa cells, whereas 293 cell-dominant factors were shown to bind only to RP–2 element. Therefore, both RU–1 and RP–2 elements were found to be necessary for efficient CAT expression from the renin promoter in 293 cells, suggesting that activation of the Ren–1 ^c promoter requires combined action between cell type–dominant and ubiquitous nuclear factors.