The present book entitled Cereals of antiquity and early Byzantine times. Wheat and barley in medical sources (second to seventh centuries AD), penned by Maciej Kokoszko, Krzysztof Jagusiak and Zofia Rzeznicka, aims at a detailed analysis of the evolution of dietetic doctrines and an assessment of the value of medical sources for historians of food. In order to achieve the goal, the authors have analysed select medical sources composed between the 2nd and the 7th centuries AD, i.e., treatises published from the moment of canonizing dietetic doctrine by Galen up to the composition of the medical encyclopaedia compiled by Paul of Aegina and the publication of the anonymous work entitled De cibis. Within this timeframe, there appeared a number of works which, following the assumptions of the Hippocratic school, contain a cohesive discourse devoted to the role of food in maintaining and restoring human health, thus allowing us to trace the development of diets during the period in question.In order to conduct their research, the authors have selected a food group, namely cereals and cereal products, starting with common and durum wheat (and including in the research hulled wheats, i.e. einkorn, emmer and spelt) and finishing with barley, since all the above-mentioned crops constituted the basis of diet of the majority of peoples inhabiting the Mediterranean. The researches have shown the history of the said cereals in the area around the Mediterranean Sea, singled out the most important products obtained therefrom, demonstrated their dietetic evaluations as presented in the sources, determined the place of cereals in cuisine and outlined their role in medical procedures.The final result of the analyses proves stability of the dietetic doctrines throughout the researched period, explains intricacies of the conceptual system developed by the medical doctors to describe cereal and other foodstuffs, defines recipes, methods and technologies profited from in food processing and outlines the place of cereal substances (both as independent medicinal agents or as ingredients included in composed medicaments) in popular medical treatment methods.