Insulin-like growth factor binding protein-3 (IGFBP-3), the most abundant circulating IGF binding protein, inhibits cell growth and induces apoptosis by both IGF-I dependent and independent pathways. The ability of IGFBP-3 to inhibit tumor growth has been demonstrated in many cancers including prostate cancer (PCa). High concentrations of androgens, that inhibit the growth of the LNCaP human PCa cell line, have been shown to have both positive and negative effects on IGFBP-3 expression by different labs. To further explore the relationship between IGFBP-3 and androgens, we examined IGFBP-3 expression in LNCaP cells. We demonstrate that IGFBP-3 expression can be induced by 10 nM of the synthetic androgen R1881 or DHT. Transactivation assays show that the 6 kb IGFBP-3 promoter sequence directly responds to androgen treatment. In silico analysis identified a putative ARE at -2879/-2865 in the IGFBP-3 promoter. A single point mutation in this ARE disrupted transactivation by R1881. Combining the data obtained from EMSA, chromatin immunoprecipitation and mutational analysis, we conclude that a novel functional ARE is present in the IGFBP-3 promoter that directly mediates androgen induction of IGFBP-3 expression. Furthermore, we found that the combination of androgens and calcitriol significantly potentiated the IGFBP-3 promoter activity, suggesting that enhanced induction of the expression of the endogenous IGFBP-3 gene may contribute to the greater inhibition of LNCaP cell growth by combined calcitriol and androgens. Since androgens are well known to stimulate PCa growth, and androgen deprivation therapy causes PCa to regress, the stimulation by androgens of this anti-proliferative and pro-apoptotic protein is paradoxical and raises interesting questions about the role of androgen-stimulated IGFBP-3 in PCa.