Dietary patterns are a set of habits regarding consumption of foods and beverages. They are often influenced by environmental or cultural particularities, and by religion. Examples of dietary patterns include the Mediterranean, Asian and Western diets, and the prudent diet. The majority of these dietary patterns suggest portion sizes for different food items, as well as giving information on the number of servings from each food group to be consumed on a daily, weekly or monthly basis. In the past, many epidemiological studies assessing the role that diet plays in health have focused upon single nutrients or food items. However, people do not eat isolated nutrients; instead they consume meals consisting of a variety of foods, with complex combinations of micro- and macronutrients. Therefore, it is becoming apparent that dietary pattern analysis may be a useful tool to use in research of this nature. In this review, two methodologies used to assess dietary patterns are described: α-posterior and α-priori pattern analysis.