【Abstract】 Objective To investigate the effect of estrogen on esktamine anesthetic efficacy through regulating the NR2B subgroup of N‑methyl‑D‑aspartate (NMDA) receptor. Methods According to the random number table method, 40 Sprague‑Dawley female rats, weighing 200‒250 g, aged 8 weeks, were divided into four groups (n=10): a control group (group C), an ovariectomy group (group OVX), a 17β‑estradiol treatment group (group E) and a 17β‑estradiol combined with the NR2B/NMDA receptor antagonist Ro25‑6981 group (group ERo). Rats in OVX group, E group and ERo group were ovariectomized, while rats in C group were received sham operation. Rats in groups E and ERo were intraperitoneally injected with 17β‑estradiol or 17β‑estradiol combined with Ro25‑6981 for consecutive seven days after ovariectomy, respectively. Groups C and OVX were injected with the equal volume of normal saline. Esktamine anesthesia (50 mg/kg) was performed 1 h after the administration on day 7. The onset and duration of the loss of righting reflex (LRR) were recorded. The levels of 17β‑estradiol in the serum were determined after LRR tests. Results Compared with group C, the onset of LRR increased, the duration of LRR decreased in group OVX and group E+Ro (P<0.05); the onset of LRR increased and the duration of LRR decreased in group E, but the difference was not statistically significant (P>0.05). Compared with OVX group, the onset of LRR decreased, the duration of LRR increased in group E (P<0.05); the onset of LRR decreased (P<0.05), but the duration of LRR was not significantly different in group E+Ro (P>0.05). Compared with group E, the onset of LRR increased, and the duration of LRR decreased in group E+Ro (P<0.05). Compared with group C, the level of serum estrogen significantly decreased in group OVX, group E and group E+Ro (P<0.05); compared with group OVX, the level of serum estrogen increased in group E and group E+Ro (P<0.05); Compared with group E, the level of serum estrogen decreased in group E+Ro (P<0.05). Conclusion Estrogen enhances esktamine anesthetic efficacy via NR2B/NMDA receptor.