Background and Objective: Few studies have investigated the association between dietary patterns and socioeconomic and demographic factors. The aim of this study was to detect major dietary patterns and assess their relationship with socioeconomic and demographic factors among 20-50 year-old women living in the north of Tehran.Materials and methods: In this cross-sectional study 460 women, aged 20-50 year- old, living in the north of Tehran were selected by stratified random sampling. Dietary data (for the previous year) was collected by a semi-quantitative food frequency questionnaire., and information on the socioeconomic and demographic factors was obtained by interview. Factor analysis was used for identifying major dietary patterns. The association between major dietary patterns and socioeconomic and demographic factors was assessed by covariance analysis.Results: Two major dietary patterns were detected: 1. Healthy Pattern (high in, fruits; yellow vegetables, cruciferous vegetables, tomatoes and other vegetables; yogurt drink, and low-fat dairy products, poultry, olives, nuts, fruit juice, potatoes, garlic, coffee, dried fruits; and legumes), and 2. Unhealthy Pattern (high in processed meat, mayonnaise, soft drinks, sweets, refined grains, snacks, industrial juice, red meat, nuts, French fries, hydrogenated fats, egg; butter, and high-fat dairy products, sugars; and organ meats). After adjustmnent for confounders, the Azari ethnic group in comparison with the Fars ethnici group (B=0.44; p<0.01), and living in District 7 in comparison with living in District 3 (B=0.39; p<0.05) were positively, and age (B=-0.04; p<0.01), university education (B=-0.34; p<0.05) and total monthly family income (B=-0.25; p<0.05) negatively, associated with the unhealthy diatery pattern. On the other hand, age (B=0.03; p<0.01), and housing surface area (square meters_per head) (B=0.21; p<0.01) had a positive, and duration of residence in Tehran, a negative, associations with the healthy pattern (B=-0.01; p<0.01).Conclusion: Socioeconomic and demographic factors influence dietary patterns of the women. It is suggested that these factors be considered in the future assessments of associations between dietary patterns and disease.