Injury to tendons, ligaments, and muscles are common patient complaints in the orthopedic clinic. Depending upon the severity of the injury, initial conservative treatment typically consists of non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, and physical therapy (1). Patients who have been recalcitrant to the aforementioned treatment or who wish to avoid invasive surgery may require a ìholisticî treatment option, such as a Platelet Rich Plasma (PRP) injection. PRP is a conservative treatment option, which has been used for over twenty-five years and has become a popular method of treatment in orthopedics (2). PRP treatment consists of one or more injections of a concentrated extract from the patientís own blood, also known as an autologous injection. This is achieved by spinning a sample of the patientís blood in a centrifuge to separate the red blood cells, white blood cells, platelets, and plasma. The concentrated ìhealing factor richî component of the plasma is then extracted from the sample. The concentrated extract is then injected directly into the site of soft tissue injury to create an inflammatory reaction to enhance tissue repair, decrease healing time, pain, and expedite return to normal function. Studies have looked at variations in the concentrations in the PRP preparation and their respective efficacy on clinical outcomes. No studies have examined whether the patientís baseline platelet serum count affects the progression of tissue repair between injections and ultimately the final clinical outcome. We hypothesize that the patientís baseline serum platelet concentration will have an effect on the outcome in regard to pain, function, palpable tenderness and perceived level of improvement. Additionally, the treated area will be evaluated with musculoskeletal ultrasound for changes in fiber appearance and tendon or tear size. The purpose of this study is to identify if serum platelet count on the day of injection affects treatment outcome.