Objectives: To detect major dietary patterns and their relation with demographic, socioeconomic, and lifestyle factors in adult women living in Tehran, Iran. Methods: In a cross-sectional study, 460 women 20-50 y of age were selected by a stratified random-sampling method. Factor analysis was conducted to ascertain the major dietary patterns, and analysis of covariance was fitted to assess the relation between demographic, socioeconomic, and lifestyle variables and adherence to major dietary patterns. Results: Two major dietary patterns were extracted: healthy and unhealthy. After adjustment for confounders, age (b = 0.31, P < 0.01), university degree (b = 0.85, P < 0.01), housing size >20 m(2)/head (b = 0.30, P < 0.01), total family income US >$500/mo (b = 0.25, P < 0.05), physical activity (h = 0.01, P < 0.05), and history of hypertension (b = 0.36, P < 0.05) were positively associated and duration of residence in Tehran (b = -0.01, P < 0.05) was negatively associated with a healthy dietary pattern. Conversely, ethnicity (Turk versus Fars; b = 0.30, P < 0.01) and smoking (b = 0.64, P < 0.01) were positively associated and age (b = -0.33, P < 0.01) was negatively associated with an unhealthy dietary pattern. Conclusion: Our findings support the association between demographic, socioeconomic, lifestyle factors and dietary patterns of the studied women. Therefore, it is suggested these factors should be considered in future studies on the association between dietary patterns and disease. (C) 2010 Elsevier Inc. All rights reserved.