Amaranth is a multifunctional culture that surpasses many others by the amount of high-grade protein, vitamins, macro- and microelements from a unit of sown area. Amaranth grains (mature seeds) contain 14-18% of protein, up to 8% of oil, about 7% of N-free extractives and up to 4% of ash. It is used as dietary cereal, for the production of baby food, medical products, in the bakery and confectionery industries, as well as in feed production. Amaranth protein in its aminoacid composition approaches the ideal protein. Amaranth protein concentrates are not inferior to soy ones. Leaves of amaranth of vegetable cultivars are used for preparing salads, soups, fried, baked, boiled and dried food products. The green mass of amaranth is a valuable feed for pigs, cattle and other animals rich in proteins and vitamins. In order to study the biological characteristics of amaranth in the mountain and piedmont zones of the Northern Caucasus, three species of the amaranth were sown for the first time: fodder (Amaranthus caudatus L.), grain (Amaranthus cruentus L.) and ornamental (Amaranthus hipochondriacus L.) ones. Taking into account the biological characteristics of amaranth, we studied its qualitative characteristics in contrasting conditions of growth of mountains and foothills. It was shown that, due to a number of biological features, amaranth seedlings in high mountains appear 7 days earlier than in the foothills and plants undergo a full development cycle. The difference between the species of amaranth depending on the altitude was revealed. The leaf area and the height of amaranth plants increase with increasing elevation above sea level, which positively affects the growth of biomass. In the conditions of high altitude the amount of pigments of the photosynthetic apparatus, vitamins, and carotene increases by 1.5–2 times. The studied species of amaranth (grain, fodder, decorative) are of interest for international practice as a starting material for accelerating selection work on productivity and stability in contrasting conditions of mountains and foothills.