Regional economic integrations are type of economic integration that construct a base for modern economic relations between countries, or in other words defined as agreement between groups of countries that belong to the same geographic region with the purpose of reducing or removing tariff and non-tariff barriers to the free flow of goods, services and factors of production between each other. The main advantages of Regional Economic Integration are: faster flow of goods and services, elimination of border problems, ensure free trade on the area within integration, etc. On the other hand there are several disadvantages: generating conflict between countries in situation of social and economic asymmetry, commercial deviation and reduction of sovereignty, increase short-term internal competition with products and national companies. This paper explains the connection between regional economic integration Mercado Común del Sur and COVID-19 crisis. The purpose of the paper is to explain the relations of the member countries before COVID-19 and to what extent they were satisfactory in terms of political, trade, and economic aspects and how much each country benefits from the integration itself. It focuses on the the effects and impacts of the COVID-19 pandemic on member states individually and on the overall regional economic integration of Mercosur, especially on the economic, political, and social aspects, the ways in which the COVID-19 crisis should be resolved, and whether belonging to the integration itself necessarily brought only positive results during the pandemic.