We report on a CMOS microelectrode array system chip for recording and stimulation of electrogenic cell cultures and tissues, featuring a sensing area of 8.09 mm2, composed of 26'400 electrodes at 17.5 µm pitch. A user-configurable selection of the electrodes can be routed to 32 stimulation units and to 1024 recording channels with 2.4 µVrms input-referred noise and 10-bit 20-kS/s A/D conversion. The system offers a versatile platform with excellent signal characteristics for a wide range of electrophysiological recordings.