ABSTRACT The provision of the population with plant-based protein is a pressing issue in the Nakhchivan Autonomous Republic. Among the leguminous crops of the world, soybean (Glycine max (L.) Merr.) occupies the largest cultivated area and is a valuable technical, fodder, and food plant whose grain and green mass contain a large amount of high-quality protein, closer in amino-acid composition to animal protein than that of most other legumes. The aim of the present research was to identify soybean samples with high productivity and a high content of protein, lysine, and tryptophan for use in future selection work in the region. Sixteen soybean varieties, obtained from the Genetic Resources Institute and the Scientific Research Institute of Agriculture of the Ministry of Science and Education of the Republic of Azerbaijan, were evaluated during 2021–2022 on irrigated gray soils in the experimental field of the Institute of Bioresources (Nakhchivan). The content of grain protein was determined by the Kjeldahl method (nitrogen × 6.25), lysine by the Muséiko–Sysoyeva method, and tryptophan by the Ermakov–Yarosh method, using an infrared analyzer (LOMO Spektran- 119M). Analysis of variance based on the two-year means revealed statistically significant differences among varieties for all three parameters (p < 0.01). The protein content varied from 27.0% (CU-4) to 34.3% (Bravo*), the lysine content from 593 to 927 (in the units reported by the authors), and the tryptophan content from 0.50 to 0.80. The varieties Bravo*, Regale*, Regalia, Regale, and Kanata were distinguished by high protein contents. Bravo* also had the highest lysine and tryptophan contents, whereas CU-4 had the lowest values for all three parameters. Cluster analysis of the biochemical indicators grouped the 16 samples into three clusters, with a mean genetic diversity index of 0.482. The varieties Bravo* and Regale* are proposed for use in future soybean selection work in the region.