PURPOSE: Double-blind, randomized, placebo-controlled trials evaluating the efficacy and safety of Platelet-rich plasma (PRP) in the treatment of Achilles tendon rupture (ATR) have been scant. This study examines the therapeutic impact of PRP injection 3 weeks after surgery in middle-aged males. METHODS: This double-blind, randomized, placebo-controlled trial included consecutive ATR patients who satisfied the inclusion criteria and was conducted from 5 September 2018 to 24 June 2021. Three weeks after surgery using the side-locking loop technique, PRP or saline was injected at the suture site under ultrasound guidance. Evaluations were conducted at predetermined intervals (6, 10, 12, 16 and 24 weeks and 1 and 2 years) after surgery. The primary outcome was the period needed to perform a bilateral heel raise, and the important secondary outcomes were the periods needed to perform a single heel raise and 20 unilateral heel raises, respectively. RESULTS: There were seven participants in the PRP group and seven in the saline group. Demographically, both groups exhibited comparable characteristics. No complications were reported. At 6 weeks after surgery, all participants achieved bilateral heel raise. The PRP and saline groups averaged 12.3 ± 2.7 and 15.7 ± 5.9 weeks to achieve a single heel raise and 14.3 ± 2.7 and 17.7 ± 4.5 weeks to achieve 20 unilateral heel raises, respectively, with no significant differences between both groups. Moreover, no substantial disparities in clinical scores, period of jogging initiation and magnetic resonance imaging tendon assessments were noted. CONCLUSIONS: PRP did not offer a distinct advantage over saline in terms of recovery from ATR in middle-aged males. This finding underscores the need to reassess the post-operative significance of PRP and highlights the importance of further research to determine its potential advantages and risks. LEVEL OF EVIDENCE: Level I.