Eighty patients with recalcitrant lateral epicondylitis were randomized to arthroscopic extensor carpi radialis brevis (ECRB) repair plus a single leukocyte-poor platelet-rich plasma (PRP) injection (n=40) or repair alone (n=40). The primary outcome of interest was tendon healing on MRI at 3, 6, and 12 months. Secondary outcomes of interest included pain (VAS), function (MEPS, DASH, PRTEE), range of motion, grip and wrist-extension strength, and time to return to work; patients and assessors were blinded. Outcomes were assessed pre-op and at 3 and 6 weeks, and 3, 6, and 12 months. Overall, the results of the study revealed no between-group differences in MRI healing or functional scores through 12 months, though the PRP group showed earlier strength gains at 6 weeks. In short, adjunctive PRP did not enhance tendon healing or 12-month function beyond repair alone, but was associated with transient early strength improvement.