Summary: The California Division of Highways investigated a wide spectrum of coatings for the protection of steel from corrosion in an aggressive marine environment for 16 years in the period 1952-1968. Evaluation of test sections of two bridges to which the coatings were applied showed that the best system after a 10-year exposure was an inorganic post-cure zinc-pigmented sodium silicate primer having a vinyl finish coat. This system was rated 9+, with 10 being perfect. Evaluation of the inorganic self-cure zinc-pigmented silicate primers will not be available for another 6 to 10 years. All other systems provided definitely inferior protection, the next best being an all-vinyl type.