Background: To compare the early clinical outcomes and Magnetic Resonance Imaging (MRI) results of Delta Medical's PEEK (polyether ether ketone) suture anchor with those of Smith & Nephew's PEEK suture anchor in patients with arthroscopic rotator cuff repair. Methods: A total of 106 patients in four different medical centers were randomly allocated into two groups: Delta Medical's PEEK suture anchor (53 patients); Smith & Nephew's PEEK suture anchor (53 patients). The MRI results and early clinical outcomes were evaluated at 3 and 6 months postoperatively. The University of California at Los Angeles (UCLA) shoulder rating scale and the visual analog scale (VAS) score for pain and range of motion were evaluated. MRI were performed at 3 and 6 months postoperatively to examine the integrity of the repaired rotator cuff tendon based on the Sugaya classification. Results: Significant improvements in pain relief, shoulder function, and functional scores were observed in both groups after surgery regardless of the suture anchor applied (P<0.001). No differences observed in the functional scores and range of motion. The assessments of UCLA scores at 3 and 6 months produced no statistical differences (P=0.885 and 0.340, respectively). The mean VAS scores in group 1 did not reveal statistical differences at 3 and 6 months after surgery compared to group 2. No significant differences in the range of motion were found at each follow-up time-point and no shifting or breakage of the anchors occurred between the two groups (P>0.01). No major intra-or post-operative complications, such as infection, and vessel or nerve injury. Conclusions: Pain relief and shoulder function were improved after complete rotator cuff repair in both groups, regardless of the suture anchor applied. The difference in functional scores and range of motion were not significant in groups 1 and 2. Delta Medical's PEEK suture anchor had a non-inferiority effectcompared to Smith & Nephew's PEEK suture anchor. Delta Medical's PEEK suture anchor was suitable for arthroscopic rotator cuff repair. Trial registration: Chinese Clinical Trial Registry ChiCTR2100051716.