Double‐label immunohistochemistry was employed to establish whether immunoreactivity for the β subtype of the oestrogen receptor (ERβ‐IR) is present in gonadotropin releasing hormone (GnRH)‐containing cells. In the immortalized GnRH cell line, GT1‐7, almost all nuclei were immunoreactive for ERβ. In the preoptic area of ovariectomized rats, more than one‐half of the GnRH neurones (52.0–63.5%) contained ERβ‐IR within the nucleus; a smaller proportion of these neurones (5–10%) displayed a particularly intense nuclear signal for ERβ. The presence of ERβ‐IR in the nuclei of GT1‐7 cells and GnRH neurones is consistent with recent reports of ERβ mRNA in these cells. Oestrogen treatment reduced the percentage of GnRH neurones with detectable ERβ‐IR. The range of signal intensity for ERβ and the incidence of the ERβ signal in GnRH neurones were comparable following double‐label immunohistochemistry involving either bright field or fluorescent techniques. These findings raise the possibility that ERβ receptors mediate direct effects of oestrogen on GnRH neurones.