The basic aim of the present study was to determine the diet of human populations dating from the Bronze Age and the time of Roman influence. The osseous material under examination came from skeletal and crematory burials of the Lusatian and Przeworks Cultures, found in a cemetery at Opatów, Klobuck District, Silesian Province. Three elements: strontium, zinc and calcium were chosen as basic diet determinants. The three elements and the proportions between them are the most frequently used factors that permit a description of the relative proportion of animal and plant protein in a diet. It was assumed that the differentiation of burial ritual was paired with a diverse mode and quality of nourishment. Interdisciplinary osteological analyses, based on physicochemical studies of the odontologic material in the context of archaeological data (culture affiliation, type of burial, grave furnishings), permit a complex analysis of the issues connected with the biology of human groups, their demographic structure or, eventually, paleostratigraphy of primeval communities. It has been found that the type of burial and the richness of grave furnishings are most closely connected with the ultimate differentiation of Zn and Ca concentrations and the value of the Sr/Zn ratio. Because the richly furnished graves are at the same time mostly skeletal burials, it cannot be unequivocally stated which of the above-mentioned factors is of paramount importance. It has also been demonstrated that representatives of the Przeworsk Culture, chronologically younger than the Lusatian one that inhabited the same geographic region, show a lower Zn concentration and a higher Sr/Zn ratio.