44 patients with Achilles tendinopathy were randomized to an ultrasound-guided injection of either an adipose-derived stromal vascular fraction or leukocyte-rich platelet-rich plasma. Outcome measures included a visual analog scale for pain, the Victorian Institute of Sport Assessment-Achilles (VISA-A) questionnaire, the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score, and MRI-measured tendon lesion size. Follow-up was performed at 15 days, 30 days, 60 days, 120 days, and 180 days. Both treatments allowed for a significant improvement with respect to baseline, with stable results up to the last follow-up. Results demonstrated significantly better scores in the SVF group at 15 days for VAS pain and AOFAS ankle-hindfoot scores, and at 30 days for the VISA-A; at all other time points, groups did not significantly differ. No significant within-group reduction in lesion size on MRI was observed in either group.