Abstract: Background and Objective: Osteoarthritis (OA) is the most common progressive joint disease considered as an inflammatory disease in the elderly and one of the main causes of physical disabilities. Limited studies have assessed the relationship between dietary patterns and knee OA. The Objective of the study was to investigate the relationship between major dietary patterns and different degrees of knee Osteoarthritis (OA) based on Kellgren and Lawrence (K and L) score in a group of Tehranian women. Materials and Methods: In this cross-sectional study, data of 231 patients was diagnosed with different grades of knee OA (age: 52.59±7.69 years). Also, anthropometric measurements and blood samples were collected in order to determine fasting blood sugar (FBS), lipid profile, hs-CRP, ALT and AST. Physical activity and food intakes information were gathered by physical activity and a semi-quantitative food frequency questionnaire (SFFQ) with 147 items. Finally, three major dietary patterns were derived from Principle Component Analysis. Results: Three major dietary patterns were extracted, "Western", "Traditional" and "Healthy". Western dietary pattern (WDP) contains high intake of junk foods, sweets-dessert-high calorie beverages, processed food, coffee and high fat dairy and low intake of fruits and vegetables. Traditional dietary pattern (TDP) characterized by high intake of red meats, organ meats, legumes, onion and potato, olive, eggs and nuts. Also, healthy dietary pattern (HDP) contains high intake of liquid oil, low fat dairy, unrefined grains, white meats and tea. Overall, total variance of the three dietary patterns accounted for 25.8%. In comparison to all patients in the lower tertile, women in the 3rd tertile of WDP were younger and less physically active. Lower physical activity, higher basal metabolic rates and fat free mass variables were observed in the 3rd tertile of the HDP (p<0.05). Among 61.5% of participants who were postmenopausal women (after stratifying based on menopausal status), participants in the higher tertile of TDP predisposed to severe degrees of knee OA (OR: 2.178, 95% CI 1.084-4.374). Conclusion: It is concluded that postmenopausal women with higher adherence to Iranian TDP in comparison to lower tertile of this dietary pattern may prone to knee OA more than two fold, due to inflammatory food groups.