Bovine blood is a potentially important source of raw material for the alimentary industry and many pharmaco-chemical industrial products. Different fractions obtained with the application of membrane separative techniques were studied, orientating our work to obtain bovine seroalbumin (BSA). Pretreatments concerning feeding, operating conditions and cleaning cycles were specially stressed in order to render a maximum of native BSA. Permeating modules containing commercial membrane elements were used to facilitate any possible scale changes. In a first step the obtained plasma was microfiltrated. This was followed by ultrafiltration with two membrane cuts of 300 and 15 kD. Finally a diafiltration process was used to separate salts and low molecular weight compounds. The obtained fractions were analyzed with conventional analytic and electrophoretic methods. The determination of permeate flux and its variation in time parameters was adequate for the application of these types of techniques. The final concentration of BSA, with a much reduced amount of salts, was 3.9 times the initial concentration. There was not much adsorption phenomena and fouling of the membrane was kept to a reduced level by washing cycles.