The large reinforced concrete seawater intake structures, which are part of a cooling system in several petrochemical plants located in the Arabian Gulf, have been catholically protected to arrest chloride-induced corrosion of the steel reinforcement. The cathodic protection systems have an operating history of 1-5 years. The design and operating features of the cathodic protection systems are described and discussed. Monitoring data of each system collected over the years since commissioning of the systems are described and discussed to evaluate performance of each system. Key words: cathodic protection, concrete deterioration, titanium mesh anodes, system monitoring, reference electrodes.