Results of a parameter study concerning the electro-ultrafiltration with alternating electric fields of aqueous solutions of bovine serum albumin are presented. The alternating electric field diminishes membrane fouling and hence yields a higher specific filtrate flux. The effect of the electric field depends on frequency (0.5-50 Hz), held strength (0-80 V cm(-1)), conductivity (1-10 mS cm(-1)), protein concentration (0.1-5 w%), and membrane material (values in brackets are the range of each parameter examined in this work). Low frequency and high held strength yield the best result for electro-ultrafiltration with alternating fields. The effectiveness of the electric field increases with rising conductivity up to the point where a limiting electrolytic current is reached. Increasing protein concentration diminishes the effect of the electric field. A new procedure to perform crossflow filtration experiments, the so-called step-change experiment, is proposed. The results of the new procedure are compared to results of conventional experiments. The step-change experiments yielded reproducible results in good agreement with conventional experiments.