The influence ofplatelet-enriched plasma (PEP) ofpain intensity was estimated using a visual-analogous scale and the Wormac questionnaire in patients with knee osteoarthrosis (KOA). Beneficial effect on all variables studied was documented within I month after the onset of therapy. It was totally absent after 3 months in severe KOA but was apparent in typical KOA. Positive dynamics throughout months 1 and 3 was observed only in patients with early manifestations of KOA. It persisted during all 12 months of the study.