The purification of sugarcane juice in the manufacture of plantation white sugar can be accomplished by juice ultrafiltration (UF). Though this concept has been suggested earlier, there is little experimental data that is representative of the actual processing conditions in a sugar mill. This work describes the results of field tests using a crossflow membrane module employing polysulphone and polyethersulphone membranes. The influence of different operating parameters, viz. transmembrane pressure (TMP), crossflow velocity, feed pH and feed pre-treatment procedure was investigated. The effectiveness of the ultrafiltration process was evaluated by monitoring the flux and permeate properties under varying operating conditions. The UF was characterised by a significant flux decline due to the membrane fouling combined with bagacillo deposition on the membrane surface. However, the permeate colour acid clarity were superior to the mill's clarified juice and the purity rise was consistently higher than that obtained in the conventional liming-sulphitation process.