Updated project metadata. the aim of this study was to isolate, characterise and compare the proteome of the IFM and fascicular matrix (FM) in the equine superficial digital flexor tendon (SDFT). We hypothesised that the proteomic profile would differ between the FM and the IFM, with greater complexity and faster turnover in the IFM. Regions of the SDFT were isolated using laser capture microdissection and the protein profile assessed using mass spectrometry. 246 proteins were identified in the IFM, and 141 were identified in the FM. 60 proteins showed a 2-fold difference in abundance between the IFM and FM, including greater abundance of collagen-III and cellular proteins in the IFM, and higher levels of collagens-I and XII, and fibromodulin in the FM. A greater number of neopeptides were identified in the IFM, indicating more rapid turnover than in the FM. There were few alterations in protein abundance with ageing, but the number of neopeptides decreased with age in the IFM specifically, suggesting a decrease in IFM turnover in aged individuals. These results support the hypothesis, showing distinct protein profiles and indicating more rapid turnover in the IFM than in the FM, which appears to decline with ageing in the IFM specifically. This may result in alterations in IFM mechanical properties in aged tendon, contributing to age-related tendon injury.