Twenty-three patients with acute lateral ankle sprain treated with a plaster cast for 10 days, were randomized to receive a platelet-rich plasma (PRP) injection or no additional treatment. The outcomes of interest included pain on a Visual Analogue Scale (VAS), the American Orthopaedic Foot and Ankle Score (AOFAS), and the Foot and Ankle Disability Index (FADI), which were all evaluated at 3, 5, 8, and 24 weeks follow-up. Results of the study found VAS pain scores to be statistically significantly reduced in the PRP group at all timepoints, except at the 24 weeks post-treatment. AOFAS were statistically significantly in favour of the PRP group only at 3, 5 and 8 weeks follow-up, whilst FADI scores were statistically significantly in favour of the PRP group at 8 weeks follow up.