The review examined the current status of research into compounds with potent STS inhibitory activities as emerging drugs against hormone-dependent breast cancer. It can be concluded from current findings that STS plays a vital role in hormone-dependent breast cancers and that further investigation is necessary to validate the novel STS inhibitory compounds that are being developed. Though Phase I clinical trials of 667 COUMATE were extremely encouraging, further clinical studies are required before widespread use of these drugs can be mandated. The results from studies using dual-targeting compounds are extremely encouraging and possibly prognosticate the future direction of endocrine therapy of breast cancers. The fact that SR16157 was found to have a 10-fold higher anti-oestrogenic activity than tamoxifen indicates that these novel compounds can target multiple ligands effectively.