Ovariectomy of immature female rats results in significant decrease in parameters in different organs. Previously we found that estradiol-17β (E₂) restored the different parameters of the different organs from ovariectomized female rats (Ovx) to values obtained in organs from intact immature female rats. E₂ stimulated creatine kinase (CK) specific activity, a hormonal-responsive marker in organs containing estrogen receptors and responsive to the hormones. In the present study, we compared the effects of E₂ with those of the phytoestrogens: quercertin (Qu), daidzein (D), genistein (G), biochainin A (BA) and their carboxy-derivatives cD, cG and cBA in immature and Ovx female rats, on CK in diaphyseal bone (Di) and epiphyseal cartilage (Ep) as well as uterus (Ut) and pituitary (Pi), when injected for 24 h with and without the SERM raloxifene (Ral), or with and without pre-treatment for 3 days with the less-calcemic vitamin D analog JK 1624F₂-2 (JKF). Ovariectomy resulted in significant reduction in the basal levels of CK in all organs tested. All estrogenic compounds tested in both animal groups stimulated CK. Ral stimulated CK in all organs except Ut, but inhibited enzymatic stimulation by E₂ and some of the estrogenic compounds in a hormonal status- and organ-specific pattern. Pre-treatment with JKF increased CK response to E₂ and to some of the estrogenic compounds in a hormonal status- and organ-specific pattern. In summary, estrogenic target organs of female rats are modulated differently in a hormonal status- and organ- dependent manner in an unknown mechanism.