Objective: The aim of the present study is to determine the association between knee inflammation and knee pain in patients with knee osteoarthritis. Methods: A total of 250 patients with knee OA were included in this study. The diagnosis was based on the American College of Rheumatology (ACR) criteria for knee OA. The severity of knee pain, stiffness, and disability were measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Results: The mean age of the patients was 50.11 ± 6.34 years. Kellgren-Lawrence grading scale and age or disease duration were positively and significantly associated, whereas none of the WOMAC sub-scores were found to be related with KellgrenLawrence grading scale (P > 0.05). On the other hand, WOMAC disability scores were significantly associated with WOMAC pain and WOMAC stiffness (P < 0.01). Conclusion: Knee pain, stiffness, and duration of disease may affect the level of disability in the patients with knee OA. Therefore, treatment of knee OA could be planned according to the clinical features and functional status.