Ovariectomy of female rats decreased metabolic activities in various organs which are restored by estradiol-17β (E₂) and phytoestrogens. We now compared the effects of E₂ with those of the phytoestrogens namely quercertin (Qu), daidzein (D), genistein (G), biochainin A (BA) and their carboxy-derivatives cD, cG and cBA on aorta (Ao) and left myocardial ventricle (Lv) in immature (Imm) and ovariectomized (Ovx) female rats, on creatine kinase (CK) specific activity, when injected for 24h with and without the SERM raloxifene (Ral) or with and without pre-treatment for 3 days with the less-calcemic vitamin D analog JKF 1624 F₂-2 (JKF). We found: 1) Ovariectomy significantly reduced basal CK in Ao by 47% and in Lv by 36%. 2) All estrogens stimulated CK in both types of rats. 3) In Ao and in Lv some of the estrogens were more effective in Imm than in Ovx. 4) The SERM Ral inhibited estrogenic stimulated CK slightly less effectively in Ovx than in Imm in both organs. 5) In Ao, pre-treatment with JKF decreased CK response to different estrogens whereas in Lv, JKF up-regulated CK stimulation only by E₂, G and D in both animals. The modulation of response by Ral or JKF might be due to effects on the level and activity of estrogen receptors leading to altered responsiveness. In summary, the estrogenic response of vascular female rat organs are modulated by ovariectomy in an organ- and substrate-dependent manner correlated with modulation of the level and/or binding activity of the different receptor(s).