tSulfated steroids function as a storage reservoir of biologically active steroid hormones. The sulfatedsteroids themselves are biologically inactive and only become active in vivo when they are convertedinto their desulfated (unconjugated) form by the enzyme steroid sulfatase (STS). Inhibitors of STS areconsidered to be potential therapeutics for the treatment of steroid-dependent cancers such as breast,prostate and endometrial cancer. The present review summarizes steroid derivatives as inhibitors of STScovering the literature from the early years of STS inhibitor development to October of 2012. A briefdiscussion of the function, structure and mechanism of STS and its role in estrogen receptor-positive(ER+) hormone-dependent breast cancer is also presented.