We previously generated and characterized a genuine estrogen receptor (ER) β-null mouse line (named ERβ _ST ^L−/L− ) and showed that ERβ _ST ^L−/L− mice were sterile, due to an ovulation impairment in females and to an unknown reason in males, as their reproductive organs and spermatozoid motility appeared normal. We report here an assessment of the sexual behavior of ERβ _ST ^L−/L− null mice. We found that ERβ _ST ^L−/L− males display mildly impaired sexual behavior and that ERβ _ST ^L−/L− females are significantly less receptive and less attractive than wild-type (WT) females. Decreased attractivity is also exhibited by ERβAF2 ⁰ but not by ERβAF1 ⁰ mutant females (females devoid of either AF2 or AF1 activation function of ERβ). Interestingly, by using an odor preference test, we have determined that the low attractiveness of ERβ _ST ^L−/L− and ERβAF2 ⁰ females is related to a deficiency of a volatile chemosignal.