To evaluate the validity of dietary patterns derived using both a priori and a posteriori methods.Five hundred individuals (46 ± 16 years, 40% males) completed a valid 76-food item food frequency questionnaire and a 3-day dairy. The MedDietScore was used to a priori assess the adherence to the Mediterranean diet, while principal components and cluster analysis were used as the a posteriori methods.Both the a priori and a posteriori methods used led to relatively low-validity dietary patterns. However, the level of validity reached significance in many cases and, also, varied by the type of validation method used (i.e. Bland and Altman, non-parametric criteria, etc.).The aforementioned findings may suggest that the use of both a priori and a posteriori pattern analysis in nutrition surveys should be made with conscious thought and further research is needed in order to establish robust methodologies to assess the validity of patterns.