The production of 20-Hydroxyeicosatetraenoic acid (20-HETE) in the kidney is thought to be involved in the control of renal vascular tone and tubular sodium and chloride reabsorption. 20-HETE production in the kidney has been extensively studied in rats and humans and occurs primarily via the actions of P450 enzymes of the CYP4A and 4F families. Recent advancements in molecular genetics of the mouse have made it possible to disrupt genes in a cell-type specific fashion. These advances could help in the creation of models which could distinguish between the vascular and tubular actions of 20-HETE. However, isoforms of the CYP4A and 4F families which may be responsible for the production of 20-HETE in the vascular and tubular segments in the kidney of the mouse are currently unknown. The goal of this study was to identify the isoforms of the CYP4A and 4F family along the nephron by rt-PCR of RNA isolated from microdissected renal blood vessels and nephron segments from 16-24 week old male and female C57BL/6J mice. CYP4A and 4F isoforms were detected in every segment analyzed with sex differences only observed in the proximal tubule and glomeruli. In the proximal tubule segments from male mice, the 4A10 and 12 isoforms were present, while the 4A10 and 14 isoforms were detected in segments from female mice. In glomeruli, sex differences in the expression pattern of CYP4F isoforms were also observed with male mice expressing the 4F13, 14 and 15 isoforms, whereas, female mice expressed the 4F13, 16 and 18 isoforms. These results demonstrate that isolated nephron and renal vessel segments express multiple isoforms of the CYP4A and 4F families, therefore, elimination of a single CYP4A or 4F isoform may not decrease 20-HETE production in all nephron segments or the renal vasculature of male and female mice. However, the importance of CYP4A versus 4F isoforms to the production of 20-HETE in each of these renal tubular and vascular segments of the mouse remains to be determined.