This paper aims to deliberate the structural performance of reinforced concrete (RC) members degraded by deterioration of constituent materials. Through tests and analyses of RC members takenout from existing piers which have been in service for more than 30 years, the following topics were particularly discussed: 1)Variation in mechanical properties of concrete and chloride ion profiles in concrete; 2) Variation in mechanical properties of corroded reinforcement in concrete; 3) Evaluation of the corrosion state of reinforcement by non-destructive electrochemical indices; and 4) Influence of the variation of materials deterioration on the structural performance of RC members. The following conclusions were drawn: 1) Test pieces should be very carefully sampled to improve the reliability of evaluation results regarding the deterioration state of RC members because the states of deterioration as well as properties of materials have wide variation. 2) Mechanical properties of corroded reinforcement are affected by non-uniformity of its cross-section. 3) Keeping the concrete in uniformly wet is important to reduce inaccuracies when measuring the non-destructive electrochemical indices. 4) The relationship is articulated between the decrease in the load carrying capacity and the deterioration grade judged by visual inspection.