Objectives: Subsistence strategies are of great interest for understanding how prehistoric societies adapted to their environment. This is particularly the case for the southern Caucasus where relationships have been shown with the northern Caucasus and Mesopotamia since the Neo-lithic and where societies are alternately described as sedentary and mobile. This article aims, for the first time, to characterize human diets and their evolution using biochemical markers, from the Neolithic to the Bronze Age (sixth-first millenium BC), at Mentesh Tepe, a site in the middle Kura valley in Azerbaijan. Materials and Methods: The data set belongs to 40 humans, 32 domestic and wild animals, and 42 charred seeds discovered in situ and perfectly dated. Stable isotope analyses were performed , including (a) δ 13 C co and δ 15 N for animal and human bone collagens and for seeds, and (b) δ 13 C ap for human bone apatite. Results: Almost all the data (25/31) suggest an increased contribution of cereals, lentils, and freshwater fish during the Neolithic, whereas afterwards, until the Late Bronze Age, all individuals consumed more animal proteins from their livestock. None of the biological criteria (age at death and sex) and burial types (mass/single graves) were found to be related to a specific diet over time. Comparisons with other isotopic data from contemporary sites in Georgia argue in favor of a wide variety of dietary sources in the vicinity of the Kura valley and for highly mobile populations. Clear evidence of millet consumption has only been found for the Late Bronze Age. K E Y W O R D S apatite, carbon and nitrogen, collagen, diet, prehistory, South Caucasus