Ferrocene, di(η 5 -cyclopentadienyl)iron(II)), has for nearly half a century now been a focal point of research activities in the realm of organo-transition-metal chemistry and physics, with ramifications into numerous technologies. More recent years have witnessed the emergence of a new research trend, probing the behavior of ferrocene in the biological realms, notably in the transformed, i.e. cancerous, cell system. Following initial reports attesting to the pronounced antiproliferative properties of certain water-soluble derivatives of ferrocene and its one-electron oxidation product, the ferricenium radical cation, earlier programs were set up in the author's laboratory with the objective of developing water-soluble polymeric conjugates in which the bioactive ferrocene unit is bioreversibly tied to macromolecular carriers in order to enhance its therapeutic effectiveness. In this article, these earlier investigations of polymer-ferrocene conjugation are briefly reviewed, and the current, considerably broadened synthetic program is introduced. The carriers are predominantly of the highly versatile poly(aspartamide) type, but other structures resulting from esteramine polycondensation reactions have been included. Carrier anchoring of the ferrocenylation agent of choice, 4-ferrocenylbutanoic acid, is brought about both by acylation of carrier-attached amino groups, leading to amide links in the spacer, and by acylation of polymer-bound hydroxy groups, resulting in ester linking of the ferrocene unit. Selected conjugates are being screened in cell culture tests for antiproliferative activity against the HeLa and LNCaP human cancer lines, and preliminary results are highly promising, with IC 50 values in the representative range of 2-20 μg Fe/ml. In view of the relatively low level of toxic side effects expected for these organoiron compounds, the findings here presented, however limited in scope, offer challenging opportunities for the development of iron-containing, polymer-anchored drug systems as chemotherapeutic agents in cancer research.