This paper presents the use of electrochemical impedance measurement on a cell chip to monitor cell growth as a consequence of treatment with potentially cytotoxic agents. The cell chip consists of an eight-well cell culture chamber incorporated with a three-electrode system on each well. The gold electrode for impedance measurements is fabricated by sputtering oil polycarbonate film. Human hepatocellular carcinoma cell (HepG2) is adapted to cytotoxicity test using the cell chip. Although the relatively small quantity of cells on the electrode has been measured indirectly, the cell chip can monitor toxic effects on the HepG2 cells cultured in the cell chip continuously and detect Cellular behavior without multiple reagents. The cells in the stationary phase after plating are used for the cytotoxicity experiment and the impedance is decreased after treatments with several toxicants, such as tamoxifen and menadione, indicating the detachment of dead cells. These results reveal that the microfabricated cell chip system provides an easy and real-time monitoring method for cytotoxicity test. (c) 2005 Elsevier Inc. All rights reserved.