Background and aim: A decreased adherence to the Mediterranean Diet (MD) may be related to a rise in chronic non-communicable diseases from childhood onward. The aim of this systematic review was to summarize the available literature regarding MD adherence in children and adolescents, and focusing, more specifically, on the association of MD adherence with demographic and anthropometric variables, body composition, lifestyle, and diet adequacy. Methods and results: A search of scientific literature was carried out on PUBMED, SCOPUS, Clinical Trials Results, Google Scholar, and British Library Inside for studies published in the last 20 years. Fifty-eight papers were finally included according to the following criteria: MD adherence evaluated through a quantifying score or index, age 2-20 years, sample size >200 participants, observational or intervention studies regarding the general population. The KIDMED index was the most widely used scoring system. MD adherence widely varied within the Mediterranean countries for both children and adolescents, with also large differences among various European countries, while few data are available for non-Mediterranean countries. Most of the eligible studies showed that MD adherence was directly associated with physical activity (and possibly with diet adequacy) and inversely with sedentary behavior, while the results for gender, age, socioeconomic status and weight status were not consistent. Conclusions: Further validation of MD indexes in terms of reproducibility and consistency with the MD is needed. At the same time, more prospective cohort and intervention studies may better elucidate the relationships of MD adherence with behavioral and health outcomes. (C) 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.