The technique of holographic interferometry used to visualize the ultrafiltration membrane surroundings makes it possible to visualize solute retention and verify whether or not there is cake formation on the membrane surface during the ultrafiltration of bovine serum albumin (BSA) protein using a polyethersulfone membrane. The experimental results indicate the presence of a gelatinous mass or a filter cake during BSA ultrafiltration using the membrane mentioned. This was shown by the small concentration profile obtained from the interferometric information and from direct observation of the membrane environs when the pump stopped, which showed the appearance of a gelatinous material adjacent to the membrane.