A microcomputer system for the processing of evoked field potentials of brain slices was developed on the IBM PC-AT microcomputer. In the system, a 385-point finite impulse response (FIR) filter was designed and fast Fourier convolution algorithm was adopted to attain both high quality of filtering and high efficiency of calculation. Also a method for wave peak recognition by analysing waveform slope was established and an interface circuit was designed for the automatic control of the FM tape recorder by the computer. As a result, automated parameter measurement of epileptiform activity recorded from hippocampal slices was successfully realized with high accuracy.