Neuromodulating activity of anti-brain autoantibodies obtained from electroshocked (ECS) rats was tested on the neurons of isolated suboesophageal ganglion of the snail Helix pomatia. In 16 out of 18 spontaneously active (pacemaker) neurons. ECS IgG containing anti-brain autoantibodies induced short-lasting epileptiform discharges and membrane depolarization. Membrane input resistance and time constant decreased, while membrane capacitance increased after addition of ECS IgG. Amplitude of evoked action potential (AP) decreased, whereas AP duration, rise time and fall time slightly increased. Thus, anti-neural autoantibody-positive IgG from rats with experimental epilepsy, but not autoantibody-negative IgG from control rats, significantly affected the bioelectrical properties of the isolated snail neurons. These results suggest that anti-neural autoantibodies present in epileptic animals are capable of influencing in vivo the function of the brain neurons.