In the recent years, organometallic compounds have become recognized as promising anti-cancer drug candidates. While radioactive (186/188)Re compounds are already used in clinics for cancer treatment, cold Re organometallic compounds have mostly been explored as luminescent probes for cell imaging and photosensitizers in photocatalysis. However, a growing number of studies have recently revealed the potential of Re organometallic complexes as anti-cancer agents. Several compounds have displayed cytotoxicity equaling or exceeding that of the well-established anti-cancer drug cisplatin. In this review, we present the currently known Re organometallic complexes that have shown anti-proliferative activity on cancer cell lines. A particular emphasis is placed on their cellular uptake and localization as well as their potential mechanism of action.