A large-scale ultrafiltration (UF) system integrated with coagulation was applied to produce drinking water from the highly turbid Taihu River. This UF installation could produce 10,000 m(3) drinking water per day. In this study, the effect of FeCl3 coagulant on the performance of the UF system was evaluated. Results showed that with the integration of coagulation, not only qualified drinking water was obtained from the high turbidity raw water, but also high UF specific flux was maintained, ca.190 200 L/m(2).hr.bar, and the chemical cleaning period was largely prolonged. The natural organic matter removal mechanism by coagulation was also discussed.