This study was conducted to identify methods that have been used in the repair and rehabilitation of concrete dams. Information was obtained through literary searches, discussions with project personnel, and visits to project sites. Each case history includes a background of the project, the deficiency that necessitated repair or rehabilitation, and descriptions of materials and methods used in the repair or rehabilitation. When available, the cost of the repair project and the performance of the repair to date have been included. Case histories included in this report cover a range of deficiencies in concrete structures, including cracking, spalling, erosion, leakage, inadequate PMF capacity, expansion resulting from alkali-aggregate reaction, instability, and insufficient storage capacity.