Sixty-seven patients with Achilles tendinopathy were randomized to receive 4 weeks of daily topical diclofenac (n=32) or placebo (n=35) for the improvement of symptoms. The primary outcome of interest was physical function measured with the Victorian Institute of Sports Assessment - Achilles (VISA-A) score. Secondary outcomes of interest included pain at rest and during loading on a pain rating scale (0-10), pressure pain threshold, tendon stiffness, patient reported global rating of change (GROC), drug compliance, and the incidence of additional treatments and adverse events. Outcomes were assessed at 4 and 12 weeks follow-up. Results revealed no statistically significant differences for the improvement in VISA-A scores, pain during loading, or pain at rest between the two groups (p>0.05 for all). Similarly, no statistically significant differences in pressure pain threshold, tendon stiffness, GROC scores, or drug compliance were observed between the two groups (p>0.05 for all). Moreover, 12 patients in the diclofenac group and 7 patients in the placebo group required physical rehabilitation treatment at some point during the study. Finally, 13 and 12 cases of gastrointestinal symptoms were reported in the diclofenac and placebo groups, respectively. 2 cases of vomiting and 1 case of stomach pains was reported in the diclofenac group, whilst 1 case of dermatitis was reported in the placebo group.