INTRODUCTION: Although muscle contusions are capable of healing, incomplete functional recovery often occurs. We have previously reported that when a safe human dose of losartan (10mg/kg/day), one of the FDA approved Angiotensin II Receptor Blockers (ARBs) and anti-fibrotic agent, that block TGF-β1, was administrated 3 days after injury it can promote functional improvement, muscle regeneration and decrease fibrosis at 4 weeks after injury [1]. Moreover, some reports have shown that PlateletRich Plasma (PRP), which includes many kinds of growth factors, including TGF-β1, can accelerate muscle healing after injury [2]. Our hypothesis that losartan treatment along with PRP can further accelerate the muscle healing process compared to the use of losartan or PRP treatment alone. The purpose of the current study is to investigate the potential functional improvement of contusion injured skeletal muscle in mice using both losartan and PRP in combination.