Platelet-rich plasma (PRP) therapy is widely used in many fields of medicine and is becoming more and more popular in the treatment of many diseases. Platelets (PLT) contain physiologically active proteins called growth factors (GFs) that accelerate the regeneration of damaged tissue. Stimulation of regeneration of damaged tissue is possible thanks to the use of patient's own blood, which must be properly prepared before administration. PRP preparation consists in concentrating the PLT several times in relation to the patient's peripheral blood. Because the treatment is based on autologous transfusion, the risk of adverse reactions is negligible, although in some situations some risk factors limit the use of PRP and may contribute to the occurrence of adverse effects. Preparation is relatively cheap and quick and can be carried out in the presence of a patient. In the literature can be found different definitions of PRP, methods of preparation, concentrations of PLT, ways of activating PLT, ways of administering PRP to damaged tissue, and finally different effects of treatment with this blood derivative. In addition, confirming the effectiveness of PRP therapy is difficult, comparing the treatment of various diseases with each other. The authors clearly emphasize the need for standardization of preparation and administration of PRP in various diseases. The lack of harmonization of preparation procedures and the way of administering PRP raises many questions and controversies, although PRP therapy is considered a promising method of treating tissue injuries. The aim of this article is to show what lies behind the concept of PRP, what is its mechanism of action as well as to show and systematize the complexity of PRP issues.