hamstring injury is the most common musculoskeletal disorder and one of the main causes of missed sporting events. Shortening the time to return to play (TTRTP) is a priority for athletes and sports medicine practitioners. platelet-rich plasma (PRP) injection at the site of severe acute hamstring injury increases the healing rate and shortens the TTRTP. Cohort study. all patients with ultrasonography and MRI evidence of severe acute hamstring injury between January 2012 and March 2014 were offered PRP treatment. Those who accepted received a single intramuscular PRP injection within 8 days post-injury; the other patients served as controls. The same standardized rehabilitation program was used in both groups. A physical examination and ultrasonography were performed 10 and 30 days post-injury, then a phone interview 120 days post-injury, to determine the TTRTP at the pre-injury level. of 34 patients, 15 received PRP and 19 did not. Mean TTRTP at the pre-injury level was 50.9±10.7 days in the PRP group and 52.8±15.7 days in the control group. The difference was not statistically significant. a single intramuscular PRP injection did not shorten the TTRTP in sports people with severe acute hamstring injuries.