Introduction: More than 50% of all shoulder pains are attributed to Rotator cuff diseases. Platelet rich plasma (PRP) is a preparation of concentrated autologous platelets containing growth factors and bio active substances essential for musculoskeletal healing. The purpose of this study is to compare the effectiveness of platelet-rich plasma injection versus corticosteroid injection with respect to pain relief and functional recovery. Methods: Sixty five patients with rotator cuff disease have been randomized into 2 groups. One group received PRP and another group received corticosteroid injection. The primary outcome pain is assessed by visual analogue scale. Secondary functional outcome is assessed by passive range of movements and WORC score at 3 weeks, 3 months,6 months and 12 months. Results: VAS score, ROM and WORC score have significantly improved up to 12 months when compared to pre-interventional scores in both the groups. The mean VAS score was significantly lower in CS group compared to PRP group at 3 weeks follow-up (p<0.05). The mean WORC score was comparable between both the study groups at 3 weeks follow-u p. (p>0.05). There were no significant differences in the WORC, ROM, or VAS scores between the two groups at 3 months, 6 months, and 12 months follow-up. Conclusion: Both CS and PRP group produced significant pain relief and functional outcome upto one year. Corticosteroid injection produced superior pain relief and improved ROM but same functional recovery compared with PRP injection for rotator cuff diseases at short term follow-up (3weeks). However, there was no statistically significant difference between the 2 groups in pain relief and functional outcomes at the mid-term (3-6 months) or long-term (12 months) follow-up suggesting both are equally effective.