The activity and toxicity of the anthracycline antibiotics are due to their redox activity, DNA and phospholipid binding capabilities, and metal affinities. We report here the study of metal-anthracycline interactions using paramagnetic Yb3(+) as a probe; a 1:1 Yb3(+)-daunomycin complex was prepared with its isotropically shifted H-1 NMR features fully assigned using 2D NMR techniques. This study provides the means for future study of the role of metal ions in anthacycline-biomolecule interactions.