The purpose of the study was to compare the effectiveness of physiotherapist-supervised and home-based exercises after platelet-rich-plasma (PRP) injection in knee osteoarthritis (OA). Thirty women (mean age = 57.83 +/- 7.26 years; mean weight = 72.13 +/- 15.54 kg; mean height = 158.40 +/- 4.49 cm; mean body mass index = 28.75 +/- 6.18 kg/m(2)) were included. Patients randomized either supervised or home-basedexercise-group after PRP. Both groups performed 6-week (3 times/week) exercise. Pain, hip and knee muscle strength, and knee functions were assessed before and after exercise. The median improvement in the pain from baseline to 6(th) week was 3.80 (2.85-5.55) point in-supervised-exercise-group while it was 0.60 (-0.10-2.55) point in home-based-exercise-group (p = 0.002). The median improvement in knee function was 22.91 (13.02-30.20) in supervised-exercise-group overtime (p < 0.001). There was no improvement in knee function following home-based exercises (p = 1.000). The supervised-exercise-group revealed a significant improvement in hip (median difference = 32.00 (8.30-88.95), p = 0.011); quadriceps (median difference = 32.10 (21.65-60.05), p = 0.001) and hamstring (median difference = 27.90 (7.95-37.65), p = 0.022) strength overtime. The physiotherapist-supervised exercises after PRP had better effects on pain and knee function than the home-based exercises.