A 64-channel amplifier system for the recording of extracellular signals with planar metal microelectrodes is presented. Gold metal microelectrodes on glass wafers were fabricated using standard photolithographic techniques. The measurement system was divided into a headstage preamplifier and a main amplifier. The inherent noise of the extracellular recording system was minimized by using an independent battery supply. The metal electrodes were directly connected to the gates of low noise junction field effect transistors (JFETs) using a specially designed electronic circuit. With this set-up, it was possible to record extracellular signals with planar metal microelectrodes without any surface modification for impedance reduction. A feedback circuit in the first amplification stage compensated slow drifts of the gold microelectrodes, which made online sampling of all 64 channels with a sampling rate of 10 kHz possible. Recordings were taken from rat cardiac myocytes cultured on fibronectin coated sensor chips. The system exhibited a good signal-to-noise ratio. It was able to detect the signal propagation within the cardiac cell layer and it could be used for pharmacological investigations involving the heart, (C) 2003 Elsevier Ltd. All rights reserved.