AbstractN‐cadherin (N‐cad) is a calcium‐dependent cell adhesion molecule which is present in the granulosa cells of the mouse ovarian follicle. This cell adhesion molecule has been implicated as a key modulator of follicular development. The regulators of N‐cad mRNA levels in the ovary have not been identified. We have examined the ability of steroids to influence ovarian N‐cad mRNA levels in vivo. Immature mice were injected with either progesterone, testosterone, 17β‐estradiol, or 17α‐estradiol. Only 17β‐estradiol caused a rapid and significant increase in the ovarian N‐cad mRNA levels. We speculate that this steroid is a major regulator of N‐cad‐mediated granulosa cell interactions in vivo. © 1995 Wiley‐Liss, Inc.