The electronic,optical,magnetic and/or structural properties of these conducting polymers,which can be synthesized by chemical and electrochemical polymerization,have been controlled and modulated by adding suitable functional groups to their backbone. Polypyrrole(PPy) and polythiophene (PTh) are probably the more thoroughly investigated parent p-polyconjugated compounds because of their remarkable properties as well as their excellent environmental stability. Among PTh derivatives, poly(3,4-ethylenedioxythiophene) (PEDOT, Scheme 1), has been found to be the most useful due to its interesting properties.[10–16] Specifically, the electrical conductivity of PEDOT is higher than that of PTh and, in addition, is considered as the most stable conducting polymer currently available. On the other hand, poly(Nmethylpyrrole) (PNMPy, Scheme 1) is a simple Ppy derivative with high electroactivity and electrochemical stability.[17] However, comparison between PNMPy and PEDOT prepared by anodic electropolymerization under identical experimental conditions revealed that the electrical and electrochemical performances of the latter material are significantly higher than those of the former. The application of conducting polymers at the interface between biology and electronics is becoming an area of great importance.[5] Specifically, the interaction of conducting polymers with both biomolecules (. aminoacids, proteins, enzymes, DNA) and living organisms () are interesting for biomedical applications because the intrinsic properties of these materials can influence the molecular and cellular bioprocesses. From a practical point of view, the integration of produced conducting polymer with biosystems has been useful for the development of applications such as implants for tissue engineering[19–22] or nerve regeneration,[23–25] mechanical actuators (artificialmuscles),[26] sensors,[27,28] etc. The development of bioactive platforms based on conducting polymers, . electroactive substrates, for cell adhesion and proliferation is a valid strategy to use these materials for different biomedical applications (. tissueengineering and orthopedics).[22,29–32] Within this context,in a very recent study we examined the adhesion and proliferation of epithelial cells Hep-2 on the surface of PEDOT films.[22] The electroactvity of PEDOT, which was determined by cyclic voltammetry (CV), was found to increase significantly when it is covered by a cellular monolayer. In this work we present a comprehensive study about cellular adhesion, proliferation and viability on two pure conducting polymers, (PEDOT and PNMPy) and a multicomponent system formed by two layers of PEDOT separated by one layer of PNMPy (PEDOT/PNMPy/PEDOT, hereafter denoted 3l-PEDOT/PNMPy, where 3lmeans 3-layered) using four different types of cells.