Purpose. To investigate aB-Crystallin expression and localization in the lacrimal gland and tear fluid. Methods. Mouse, rat, porcine, monkey and human lacrimal gland samples were immuno-histochemically and immuno-electron-microscopically stained with various antibodies against aB-crystallin. Western- and Northern-blotting was performed to demonstrate the presence of aB-crystallin mRNA and protein. Human tear fluid was analyzed for the presence of aB-crystallin using dot blotting. Results. aB-Crystallin is located in the lacrimal gland duct cells but not in the acini. Electron microscopically, the protein was frequently found in apical electron-dense granules of lacrimal duct cells, occasionally also in the duct lumina. Western blotting confirmed the presence of aB-crystallin in the lacrimal gland, Northern blot samples revealed the presence of aB-crystallin mRNA. In the human tear fluid, aB-crystallin was present in all samples investigated. Conclusions. We demonstrate for the first time that aB-crystallin is present in the lacrimal gland. Presence of the protein in apical secretory granules as well as presence in the tear fluid might indicate secretion of aB-crystallin into the tear fluid.