The results of a test are presented in which concrete specimens treated with different water repellent agents have been exposed to cyclic seawater shower for one year. The objectives of the test were to examine the effectiveness of water repellent treatments as a chloride barrier for cracked or un-cracked concrete under marine environment. The test results indicate clearly how cracks in concrete influence the effectiveness of water repellent treatment as a chloride barrier. It is concluded that a careful assessment of cracks in reinforced concrete structures before a water repellent treatment is very important to determine the most appropriate application technology. [This abstract is not included in the PDF]