Osteoarthritis (OA) is a chronic degenerative disease of articular cartilage that causes hypertrophic changes in bone. OA is a non-inflammatory progressive musculoskeletal disease and is one of the most common degenerative diseases in the general population. OA is characterized by progressive cartilage destruction in load-bearing joints, subchondral sclerosis, osteophyte formation, and some biochemical and morphological changes in the synovial membrane and joint capsule. Common symptoms of knee osteoarthritis are; Knee pain that increases with activity, limitation of normal joint movement of the knee, edema, and knee pain that begins with prolonged sitting. The aim of this study is to evaluate the effects of laser treatment applied in addition to conventional physiotherapy on pain, function, muscle strength and balance in patients with knee osteoarthritis who received PRP.