We demonstrate the first realization of immuno-Raman microspectroscopy, a novel methodology in immunohistochemistry. The in situ detection of antigens in tissue specimens is achieved by surface-enhanced Raman scattering (SERS) from aromatic Raman labels covalently linked to the corresponding antibody. As an example of applications of this new Raman technique, we present the localization of prostate-specific antigen (PSA) in-epithelial tissue from patients with prostate carcinoma (PCA). Copyright (C) 2006 John Wiley & Sons, Ltd.