The scientific community has long been interested in the overall quality of diets owing to the fact that it is important for each individual's health through a healthy, varied, and balanced diet. Much research has been conducted on methods used to measure dietary quality. These studies led to the determination of numerous indices, some very simple and some much more complex. Indices that examine diets for several attributes concurrently are able to provide a measure of overall diet quality that is not possible when only single nutrients or food groups are examined. Using these indices, diet quality may be evaluated in relation to nutrient adequacy, compliance with dietary guidelines, or nutrition recommendations, association with risk of chronic diseases, or mortality, and used to assess interventions. However, there are several factors that should be taken into consideration for the design of an index, like the purpose of its use, as well as its simplicity in daily practice. The general purpose of an index is to synthesize a large amount of information into a single useful indicator. The purpose of this review was to present and to critically review the most commonly used dietary indices, and how they reflect various aspects of diet quality. The majority of these indices fail to recognize the various inter-relationships between their components, as well as their accuracy for estimating specific health outcomes. Thus, the development of weighted dietary indices that adequately assess a dietary pattern and its relationship to the burden of a disease is considered essential.