Transitional metals have a large variety of coordination numbers and geometries, accessible redox states in physiological conditions and a wide range of thermodynamic and reactivity properties which can be successfully tuned by selection of suitable ligands. These characteristics can be used to develop new drugs with numerous advantages over the organic based drugs. Historically, research in this field has focus on platinum and DNA targeting; however, anticancer drug research may be expanded to include alternative metal compounds with different mode of action resulting in markedly different cytotoxic response profiles. Cooper complexes with selected ligands are being extensively studied as agents for the treatment of cancer. Current research on copper compounds as antitumoral compounds is being reviewed in this chapter particularly focused on the family of copper Casiopeinas.