Biofouling control of cooling water systems has been one of the severe problems for power plant operation. A lot of works have been carried out and many physical/chemical control methods are available. However, practical measures satisfied following criteria have not been developed: (1)reliable control for a long enough term, (2)broad availability, (3)low environment impacts, (4)simply operating, and (5)reasonable cost. Power plants have been coping with biofouling, using a combination of some measures applicable. Possible research targets of practical anti-biofouling are discussed from a user's view.