SS-31 (Szeto-Schiller-31, MTP-131) is a mitochondria-targeting tetrapeptide that accumulates in the inner mitochondrial membrane, where it binds to cardiolipin and may protect against oxidative damage. Research suggests it can enhance ATP production, stabilize mitochondrial cristae, and reduce reactive oxygen species. Preclinical studies indicate potential benefits in conditions such as diabetic retinopathy, aging-related cardiac decline, neurodegeneration, kidney injury, cachexia, and tendinopathies. Currently, SS-31 remains available strictly for research purposes and is not approved for clinical use.