Using in situ hybridization on whole-mounts and sections of mouse embryos we have visualized the pattern of expression for the Eph receptor ligand ephrin-A5. Non neuronal expression domains include the ectoderm of the branchial arches, the ectoderm and mesenchyme surrounding the dorsal root ganglia, the intervertebral discs, maxillary and mandibulary mesenchymal elements as well as the nasal mesenchyme and ectoderm. Within the developing nervous system, ephrin-A5 expression is very dynamic. Besides the midbrain it is also expressed in the hypothalamus, and the neurohypophysis that we studied here in more detail. Hypothalamus expression of ephrin-A5 demarks distinct nuclei, persists throughout embryonic development, and can be seen also in the adult.