ABSTRACT Background Platelet-rich plasma injection has become an effective treatment for partial rotator cuff tears. This study evaluates the efficacy of PRP versus steroids injection in pain relief for partial rotator cuff tears. Study design Prospective clinical trial. Setting Alexandria Main University Hospital. Patients and methods Sixty patients with symptomatic partial RCTs undergoing US-guided subacromial injection were randomly allocated into two equal groups: either steroids or PRP. Pain score, shoulder function, failure rate after injection, and complications were recorded. Results VAS score was significantly lower in the steroid group at week 2 follow-up than the PRP group (p 0.001). However, it was shorter, extended for 8 weeks in steroid in comparison to 4 months in PRP group. There was an insignificant difference among groups in the simple shoulder test at 2 and 4 weeks follow-up, and the test was significantly higher in PRP group at 6, 8, 12 weeks, and 4 month follow-up (P = 0.049, 0.001, 0.001, 0.001). Pain did not improve in six patients in steroid group and one patient in PRP group. Pain on injection was reported by six patients in the steroid group and 13 patients in PRP group (p = 0.052). Elevated blood sugar was significantly higher in the steroid group after the injection (p 0.001). Conclusion Subacromial PRP injection may have a prolonged analgesic effect and superior shoulder functional improvement than steroids in patients with partial RCTs.