Amaranth flour--a product of amaranth seeds processing--is a valuable industrial raw material that has an unique chemical composition and may be used for nutrition of people suffering from intolerance to traditional cereals protein, including celiac disease patients. The research aim was to study the composition of amaranth flour of two types compared with semolina which is traditionally used for nutrition by Russian population, as well as to compare the composition of milk amaranth flour porridge with milk semolina porridge. The composition of amaranth whole-ground flour and amaranth flour of premium grade processed from amaranth seeds grown in Voronezh region has been researched. It is to be noted that protein content in amaranth flour was 10.8-24.3% higher than in semolina, and its biological value and NPU-coefficient were higher by 22.65 and 46.51% respectively; lysine score in amaranth flour protein of premium grade came up to 107.54%, and in semolina protein only 40.95%. The level of digestible carbohydrates, including starch, was lower in amaranth flour than in semolina by 2.79-12.85 and 4.76-15.85% respectively, while fiber content was 15.5-30 fold higher. Fat content in amaranth flour of premium grade was 2,4 fold lower than in whole-ground amaranth flour but it was 45% higher than in semolina. The main advantage of amaranth flour protein compared to wheat protein is the predominance of albumins and globulins and a minimal content of prolamines and alpha-gliadin complete absence. The specifics of chemical composition allow the amaranth flour to be recommended for being included into nutrition of both healthy children and adults and also celiac disease patients.