Elf5 belongs to the ets family of transcription factors and was cloned by homology in the DNA binding domain to the related, epithelial-specific ets factor, Elf3. Elf5 mRNA is expressed highly in normal tissue rich in secretory epithelial cells, including mammary gland, lung, kidney, prostate, salivary gland and stomach. The function of Elf5 and the cell types in which it is expressed remain uncharacterised. The presence of Elf5 mRNA in normal tissues, but absence in cancer tissues, may suggest a role for Elf5 in differentiation and development. We have generated a rabbit antiserum directed against a peptide in the Elf5 DNA-binding domain that is conserved between murine and human sequences. The antiserum specifically detects human and murine Elf5 proteins on western blots and shows specific staining on paraffin-embedded sections obtained from tissues including mammary gland, kidney, salivary gland and stomach. Epithelia from the bladder lining, lung and prostate did not stain for the presence of Elf5, though these organs express Elf5 mRNA. We show for the first time that Elf5 is primarily expressed in epithelial cells and is likely to be an epithelial-specific protein. The antiserum should prove useful in further analysis of the expression and function of Elf5.