In the Republic of Mari El spring barley is grown mainly for animal feed, but if agricultural practices are followed its grain can also be used as raw material for brewing. The purpose of the research was to study the issues of biological protection of spring barley from root rot in the Republic of Mari El. Field studies were carried out on the experimental fi eld of the Mari State University. Studies were conducted to determine the effectiveness of biological protection using the microbiological fertilizer with fungicidal action Bioagro-Gum-V, as well as the biological product Pseudobacterin-2 against seed infection, pathogenic complex of the rhizosphere and rhizoplane of spring barley. The role of biological protection in increasing the yield and phytosanitary condition of spring barley grain was revealed. It was found that the cultivation of spring barley using biological protection provided high net income, profitability and low cost of grain. The most cost-effective was the combined use of the Bioagro-Gum-V fungicide fertilizer for seed treatment and spraying of crops during vegetation with the Pseudobacterin-2 biodrug,where the net income was 30.50 thousand rubles/ha, the profi tability level was 150 %, and the cost price of spring barley was 6.80 thousand rubles/t. Production tests conducted at a farm in the Republic of Mari El confirmed the results obtained, as the yield of spring barley increased by 0.76 t/ha compared to the basic technology reducing production costs and increasing net income and profitability.