The compounds that bind steroid hormone receptors including estrogen receptors (ERs), progesterone receptor (PR) or androgen receptor (AR), and induce or modulate a steroid hormone receptor-mediated response could be defined as endocrine disruptors (EDs). Currently, there are no standard methods to determine whether a chemical is an endocrine disruptor or not. Most results of in vitro and in vivo data are derived from assays that measure estrogenic activity, thus fewer data are available from assays that measure androgenic and progestogenic activities. In this review, we introduce a novel in vivo model to detect EDs using immature rats in the induction of Calbindin-D_9k (CaBP-9k) mRNA and protein by estrogenic compounds. In addition, we summarize other biomarkers and screening methods for EDs in mammals to describe the usefulness of indicated biomarkers, although mammalian models are very few based on experimental findings.