Recently, nutrition scientists have tended prefer to assess diet-disease relations through dietary pattern approach rather than previous traditional approaches (nutrient- or food-oriented approach). Identifying dietary patterns allows us to consider the whole diet, not ingredients a relationship helps to find associations beyond those described based on foods or nutrients. This approach is also beneficial when traditional analyses in nutritional epidemiology show weak associations. Dietary pattern approach is more realistic than the food- or nutrient-based approach. Inter-correlations and biological interactions between foods and nutrients confound the associations of single foods or nutrients with a certain chronic disease. Several studies have provided evidence supporting the use of dietary pattern approach in nutritional epidemiology. Most of these studies have indicated that dietary patterns identified by factor or cluster analysis are significantly associated with chronic diseases. Data on major dietary patterns in developing countries, including Iran, are scarce. This review aims to provide more detailed information about methods of measurement, as well as the advantages and disadvantages of dietary pattern approach to help and encourage nutrition scientists in the country to use this approach in future investigations.