We synthesized a novel anticancer agents based on mixed chelate copper (II) complexes, named Casiopeínas((R)) has of general formula [Cu(N-N)(N-O)H(2)O]NO(3) (where, N-N = diimines as 1,10- phenanthroline, 2,2-bipyridine, or substituted and N-O=aminoeidate or [Cu(N-N)(O-O)H(2)O]NO(3) (where NN= diimines as 10-phenanthroline, 2,2-bipyridine or substituted Casiopeínas I, II, IV, V, VI, VII VIII and O-O=acetylacetonate, salicylaldehidate Casiopínas III). We evaluated the in vitro antitumor activity using a human cancer cell panel and some nurine cancer cells. Eleven Casiopeinas are evaluated in order to acquire some structure-activity correlations and some monodentated Casiopeinäs analogues; cisplatinum was used as control drug. The 50% growth inhibition observed is, in all cases reach with concentrations of Casiopeina's 10 or 100 times lower than cisplatinum. In a previous work we reported the induction of apoptosis by Casiopeina II. The results indicate that Casiopeinass are a promising new anticancer drug candidates to be developed further toward clinical trials.