Purposes. The updated and substantiated understanding of the patterns of the upper jaw growth in prenatal ontogenesis contributes both to the diagnosis of congenital malformations and the prevention of prenatal injury to the maxillofacial area. In this regard, determining the density of bone tissue, that is, its mineralization, whose impairment forms the basis for the development of various defects, is as important as studying inter-tissue relations in the process of histo-and organogenesis, including epithelio-mesenchymal ones. This research was conducted to study the quantitative content of trace elements (K, Fe, Co, Sr, Zn) in the dynamics of prenatal ontogenesis as a fundamental material of bone tissue. The research was carried out as part of the implementation of a fragment of the planned comprehensive research work "Features of morphogenesis and structural and functional peculiarities of tissues and organs in human ontogenesis", No. of state registration 0116U002938.Methods. By means of atomic emission (AES) and atomic absorption (AAS) spectrometry and statistical processing, as well as variational and dynamic analysis programs, the relative values for each Section 2. Medical and Biological Sciences 24 trace element were obtained while studying the bone tissue from abortion and sectional material of the upper jaw in 131 human fetuses (Ukrainians).Results. These results as the mean value of the studied parameter (M), standard deviation (m), paired student's t-test or reliability value (t), and the probability level, which are shown in Tables 2-4, where the comparison values of the first and fourth groups are: for potassium (K) -0.188 ± 0.006 in the first and 0.144 ± 0.019 in the fourth group (t = 2.21, p < 0.05); for iron (Fe) -0.348 ± 0.027 and 0.435 ± ± 0.057(t = 1.38, p > 0.05); for cobalt (Co) -0.086 ± 0.006 and 0.059 ± 0.008 (t = 2.70, p < 0.01); for zinc (Zn) -0.905 ± 0.035 and 0.303 ± 0.032 (t = 12.81, p < 0.001), which substantiates the high reliability of the findings, the quantitative determination of the content of trace elements simultaneously reflects the quality of the bone tissue of the upper jaw of human fetuses in prenatal ontogenesis.The investigated growth rate (%) for potassium (K) in the three groups is negative: between the first and second groups (-4.39%), between the second and third (-68.94%). However, a sharp increase in potassium in the fourth group, compared to the third one, is + 318.63%. The overall growth for potassium between the first and fourth groups is + 24.33%.The dynamics of iron trace content (Fe) has a positive growth pattern in almost all age periods of prenatal ontogenesis; accordingly, there is a positive growth rate (%): between the second and third groups it increases by 34.62%; between the third and fourth -by 52.15%; between the first and the fourth -by 102.67%, except for a moderate decline in the second group (17-24 weeks), therefore, the growth rate between the first and second groups has a significant but negative value (-1.05%). The maximum growth rate (%)...