The application of the high rate ADUFR (Anaerobic Digestion - Ultrafiltration) process to brewery effluent was investigated over an 80 day test period. Performance data on both the anaerobic digester and ultrafiltration unit is presented. At stabilised conditions, space load rates of 15 kgCOD.m−3.d−1 could be achieved at hydraulic residence times of 0.5-0.8 days, with COD removal efficiencies between 96 and 99%. Linear flow velocity across the membrane surface and suspended solids concentration of the biomass were found to have a substantial effect on ultrafiltration membrane flux. No membrane fouling was experienced throughout the test period and flux values of 10-18 l.m−2.h−1 (LMH) could be maintained without resorting to chemical cleaning. Dormant sludge was reactivated rapidly, after a two month rest period. A space load rate of 8 kgCOD.m−3.d−1 at a retention time of 0.5 days could be reached within seven days from restart.