Soybean (Glycine max (L.) Merrill) is one of the most important commodities in the world, with grains that show variations in their chemical composition, mainly in oil and protein content. These variations can be related to genotype (G), environment (E), and G × E interaction. Thus, the objectives of this study were to determine the environments which maximize oil and protein yields, and to identify potential soybean cultivars that have increased grain yield, and oil and protein content in high-and low-altitude environments. Twenty-eight soybean cultivars were evaluated at high (846–963 m, Cfb climate) and low (336–480 m, Cfa climate) altitude environments, in the 2017/18 and 2018/19 crops, for grain yield, thousand grain weight, and oil and protein contents and yields. Growing environment affected the chemical composition of soybean grains. Altitude had a positive effect on protein content and a negative effect on oil content. The high-altitude environment increased the protein content by 6.15% (380 g kg-1), whereas the low altitude environment promoted an increase of 5.58% in oil content, with a mean value of 220 g kg-1. We identified soybean cultivars with potential for greater oil and protein yields in high-and low-altitude environments. Knowledge of the associations between environments and the chemical composition of soybean grain is valuable for developing direct breeding efforts, recommending cultivars and growing locations, in order to meet the demand of the oil and protein market