To study the distribution of alpha B-crystallin, formalin-fixed preparations of the inner ear of the rat, cynomolgus monkey, rhesus monkey and human were stained immunohistochemically for alpha B-crystallin. In all cochleae investigated, intense staining for alpha B-crystallin was found in the inner and outer pillars as well as in the cells of Hensen and Claudius. In the primate inner ear, alpha B-crystallin was also present in the polygonal epithelial cells of Reissner's membrane, the interdental cells and some fibrocytes of the spiral limbus, epithelial cells of the outer spiral sulcus and the Schwann cells of the 8th nerve. In the primate stria vascularis, alpha B-crystallin was mainly seen in the basal cell layer and the adjacent cells of the connective tissue layer. alpha B-crystallin was found to be present in a large variety of cells in the inner ear surrounding the scala media.