Adhesion of mammalian cells to in vitro surfaces is an area of active research and it attracts considerable interest from various scientific disciplines, most notably from medical technology and biotechnology. One important issue in the context of cell-surface adhesion is the time course of attachment and spreading upon surfaces that are decorated with proteins to make them cytocompatible. This article reviews two emerging non-microscopic techniques capable of monitoring the adhesion process label-free and in real-time. Both approaches, electric cell-substrate impedance sensing (ECIS) and the quartz crystal microbalance (QCM), are based on substrate-integrated transducers that transduce cellular adhesion into an electrical signal. A short introduction of both techniques is followed by a set of examples that illustrate the performance of these sensors, their individual merits and limitations. In order to analyze the integral and complex signals of both sensors in contact with mammalian cells in more detail, we also studied their individual readouts during the adsorption of liposomes with well-defined structure and chemical composition. (C) Koninklijke Brill NV, Leiden, 2010