Аннотация:Reviews of the current state of the problem of the application of X-ray fluorescence analysis (XRF) in biology and, in particular, in the study of the chemical composition of food products, showed that XRF can be successfully used to study such problems. This chapter provides an overview of the current state of the problems troubling the use of XRF in the study of chemical composition of tea and coffee. Tea in the Krasnodar region has been grown since the beginning of the twentieth century. Estimates of interelement effects on the intensity of analytical lines for tea, coffee and some plants are presented. The Student's test was used to evaluate the two quantitative data sets obtained by total reflection X-ray fluorescence (TXRF) and wavelength dispersive X-ray fluorescence (WDXRF). The findings showed that TXRF is a fast and simple method of controlling the quality of tea and grass samples.