The storage of packed red blood cells (RBCs) is associated with the development of morphological and biochemical changes leading to a reduced posttransfusion functionality and viability of the cells. Within this study, 2D DIGE and high-resolution/high-accuracy Orbitrap MS were used to analyze the storage-induced changes of the cytosolic RBC proteome and identify characteristic protein patterns and potential marker proteins for the assessment of RBC storage lesions. Leukodepleted RBC concentrates were stored according to standard blood bank conditions for 0, 7, 14, 28, and 42 days and analyzed by using a characterized and validated protocol. Following statistical evaluation, a total of 14 protein spots were found to be significantly altered after 42 days of ex vivo storage. Protein identification was accomplished by tryptic digestion and LC-MS/MS and three proteins potentially useful as biomarkers for RBC aging comprising transglutaminase 2, beta actin, and copper chaperone for superoxide dismutase were selected and validated by western blot analysis. These can serve as a basis for the development of a screening assay to detect RBC storage lesions and autologous blood doping in sports.