The research objective is an analysis of the participation of the Black Sea Basin countries (Ukraine, Russia, Kazakhstan, Bulgaria and Romania) in world grain trade. We started this research before the start of Russia’s military actions in Ukraine, and completed it during these actions, so we have a vision of the situation before and after start of war. Subject of research: stability of grain supplies (wheat, corn, barley) from the Black Sea region as a whole and from some of its countries. Results of the research: The research revealed the growing role of the Black Sea region in the pre-war period in the world grain market and identified its key leaders. The share of the Black Sea region in world trade in wheat increased to 34%, barley – to 40,6%, corn – to 25,3% in 2019/2020 marketing year. The calculated coefficients of variation confirmed the decrease in the scattering of grain exports in 2015-2020 vs. 2010-2015, which indicates an increase in stability and reliability of supply in this period. The situation changed radically after the Russian invasion of Ukrainian territories. The maritime logistics corridors of Ukraine that is the one of the key players in this region, were blocked and started working only five months later, but not at full capacity. All these events had its destructive consequences for world trade, in particular, the increase in world prices, disruption of the stability of grain supplies from the Black Sea region and the destruction of established logistics corridors, etc.