Rotator cuff tear is a common reason for shoulder pain. Although the surgical technique of rotator cuff repair is developing, high retear rate requires additional supplementary methods. Among these supplementary methods, as a kind of biologic augmentation, platelet-rich plasma (PRP) has been spotlighted and has recently been studied by many researchers. PRP, a concentrate of platelet extract obtained from whole blood, contains numerous growth factors. As this is known to play an important role in the tissue recovery process, it had been used for research in a variety of fields including orthopedics. Use of PRP has been attempted in surgical treatments of rotator cuff tear for better results; however, only a few large-scale research studies on the effect of PRP have been reported. Clinical results of each study are also variable. Therefore research using large-scale randomized, double-blind trials should be conducted in order to prove the application range, safety, and clinical effects of PRP.