The Evaluation of Knee Joint Compartments by Kellgren Lawrence System in Knee Osteoarthritis The aim of this study was to evaluate the disease severity of knee joint compartments by using Kellgren-Lawrence radiologic system in knee osteoarthritis patients. We also looked for associations among radiologic scores and several clinical parameters. Forty-one (41) knees of  21 knee osteoarthritis patients (5 male, 16 female, mean age: 62,6 + 9.2, range: 44-76) were examined in the study.  There were statistically significant differences among radiologic scores of the compartments (p=0,000). Lateral tibiofemoral compartment scores were significantly lower when compared with medial tibiofemoral (KLmed) (p=0,000) and patellofemoral (KLPF) (p=0,000) compartments. The difference between patellofemoral and medial tibiofemoral scores were not statisticaly significant (p=0,835). Kellgren-Lawrence scores of all compartments correlated with disease duration; KLmed, KLPF and KLmaks (the highest score of three compartments) correlated with age; and KLmaks correlated with rest pain. No associations were found among radiological scores and body weight, height, body mass index, morning stiffness and walking pain. The radiological disease severity of knee joint compartments were arranged as patellofemoral-medial tibiofemoral and lateral tibiofemoral in knee osteoarthritis patients. The frequencies of compartmental involvement were similar in arrengement in a previous study. When performing diagnostic and therapeutic procedures, physicians should first focus on the compartments effected severly and frequently by disease process in knee osteoarthritis patients.