Neurofibromatosis type 2 (NF2) is an autosomal dominant disease in which loss of function mutations of the NF2 gene lead to the development of schwannomas, meningiomas and juvenile cataracts. We studied the mouse NF2 homologue (Nf 2) to determine its precise pattern of mRNA and protein expression. In situ hybridization showed that Nf 2 is expressed in neuronal cells as well as in epithelial and fibre cells of the lens. The Nf 2 protein, schwannomin, is expressed as a single protein isoform of ~80 kDa in neuronal and nonneuronal tissues. In Purkinje cells of the cerebellum and motor neurones of the spinal cord, the protein is in the cytoplasm. In non-neuronal tissues immunostaining showed expression in cells of the tunica intima of blood vessels. We conclude that there is a widespread but cell type-specific expression of schwannomin.