Aims: (i) To quantify the mRNA levels of GHRH, ghrelin and their receptors in malignant and adjacent normal breast tissue, and (ii) to determine any correlation between such expression and that of the tumour associated genes, PCNA, c-myc, Cox-2 and VEGF 189. Methods: Total RNA was extracted from 60 samples of paired normal breast epithelium and carcinoma. mRNA levels of each gene were quantified using a real time, hydrolysis probe-dependent RT-PCR assay (‘Taqman’), and expressed as log copy no./µg total RNA. Results: Expression of GHRH, GHRH-R and GHS-R 1a was absent in all specimens of normal and malignant breast tissue. Ghrelin mRNA was expressed in all samples of normal tissue and cancers, but there was no significant difference between the two (median level: 1.6 × 105versus 2.1 × 105 copy no./µg total RNA, respectively). In normal breast tissue there was a significant correlation between ghrelin mRNA levels and those of all genes studied. Weaker correlations were present in the cancers. Conclusion: The universal expression of ghrelin and its association with that of genes implicated in breast tumourigenesis suggests a role for ghrelin in both the maintenance of normal breast tissue and tumourigenesis. The absence of the GHS-R 1a strongly implies that the effects of ghrelin are mediated via a novel receptor. Whether these effects are independent of the GH/IGF-I axis remain to be determined.