Probabilistic methods of structural reliability are applied to investigate failure of reinforcement protection when the carbonation depth exceeds the concrete cover. The proposed method of probabilistic optimization indicates that the optimum thickness of the concrete cover is strongly dependent on the ratio of the malfunction cost and the marginal cost per unit of concrete cover, and on the required design life of a structure. It appears that commonly used concrete covers may not be adequate. Additional data and improved optimization models are, however, needed. Most important topics of foreseen research are indicated.