The ErbB family of receptor tyrosine kinases contribute to human prostate cancer, however, ErbB activity in the normal prostate requires further investigation. The mouse prostate may serve as an important model system to study the molecular mechanisms regulating ErbB signaling in the prostate. We employed RT-PCR and immunohistochemistry to perform a comprehensive expression profile of ErbB receptors and ligands in the mouse prostate. Physiological receptor activation in situ was measured by receptor phospho-tyrosine analysis. Expression of all four ErbB receptors and the EGF-like ligands EGF, TGF alpha, AR, beta C, Hb-EGF, NRG1, and NRG3 was detected in the mouse prostate. We failed to detect expression of the ErbB ligand, ER. Physiological receptor activation was observed within the mature mouse prostate at 10 weeks but not in the prostates of 3- or 6-week-old mice. Coordinated ErbB receptor and ligand expression coupled with receptor activation profiles provide strong evidence that ErbB signaling contributes to mouse prostate function.