Numerous proteins responsible for cell proliferation and differentiation exist either as hetero or homodimers or become activated through dimerization as a key step in their respective signaling cascade. Many of these proteins have been identified as major components in oncogenic signaling pathways and have become popular targets for the development of anti-tumor agents. For this reason, bivalent anti-cancer drugs that could potentially interact with each monomer of a dimeric protein target have been developed. This review provides a brief background on prevalent dimeric drug targets within the anti-cancer field and focuses mainly on dimeric natural product and synthetic cancer chemotherapeutics.