The invention relates to the use of microRNA 29 and precursors and mimics thereof for the modulation of tendon injury and the biomechanical properties of tendon. In particular, the invention derives from the finding that synthesis of type 1 collagen in tenocytes is less sensitive to miR-29 than is synthesis of type 3 collagen, thus enabling the balance between the collagen subtypes to be modulated in favour of type 1 collagen, mitigating reduction in biomechanical properties during healing.