Introduction. The possibility of using NIR spectroscopy to determine oleic acid in sunflower seeds has not been studied, so research on this field is perspective.Materials and methods. The spectra of seed samples of various sunflower varieties with a known content of oleic acid and the same samples additionally enriched with oleic acid were investigated by NIR diffusion reflectance spectroscopy with using the instrument "Infrapid-61". To process the results obtained, the methods of mathematical analysis were applied.Results and Discussion. In the NIR spectra of samples of dried sunflower seeds, in comparison with the spectra of raw seeds, the expected decrease in the coefficient of diffuse reflection is observed in the range 1920-1940 nm related to the moisture content in the sample. Analysis of NIR spectra of a calibration series of dried seeds enriched with oleic acid shows an increase in the coefficient of diffuse reflection in the wavelength ranges 1920-1940 nm and 2140-2160 nm in proportion to the growth of the mass portion of oleic acid. Corresponding calculations, calibration curves and the obtained equation describing the dependence demonstrate a linear dependence of the reflection coefficient on the mass portion of oleic acid in the sample at the wavelength of 2140 nm with a confidence level of 98%. The dependency found can be used for the quantitative determination of oleic acid in a sunflower seed sample of unknown composition. By the magnitude of the coefficient of diffuse reflection of the sunflower seed sample containing unknown amount of oleic acid, its mass portion in the sample can be determined from the graph. The diffuse reflectance spectra of husked and crushed seed samples and corresponding spectra of crushed sunflower seeds with husks containing the same oleate amount are practically identical with the wavelength range 1330-2370 nm. Therefore, this method can be used for the analysis both intact seeds and seeds separated from husks. The express method of diffuse reflection of NIR spectroscopy can be considered as an alternative to chemical methods for determining the quality indicators of fatcontaining raw materials.Conclusions. The method of NIR spectroscopy is perspective for the determining of other fatty carboxylic acids in sunflower seeds.