Among the various applications of metal-based compounds, those that involve catalytic properties and biological activity have been the goals of quests by many research teams throughout the world. We mainly concentrate in this short review article on the anticancer properties of a certain class of organometallic ruthenium compounds: the cyclometalated derivatives that have been studied in the last decade. We emphasize the apparent contradiction between the known reactivity of the carbon–metal bonds in these species towards nucleophilic and electrophilic reagents and the fact that these bonds most probably survive the harsh reaction conditions that exist in most of the catalytic media and probably also in the biologic media. We focus on the mechanisms of action of the cycloruthenated molecules in terms of their anticancer properties and thus reveal some of the most recent findings on the potential modes of action of these compounds in cancer cells, which open new therapeutic perspectives.