This paper analyses the communication strategies involved in public relations actions in contexts of socio-environmental crises in Brazil. To do this, it starts from two emblematic cases to reflect how organisations have responded to the crises they have led to: that of Vale S.A., in Minas Gerais (MG), and that of Braskem, in Alagoas (AL), both multinational companies linked to extractive activity. The first involves the collapse of the B1 tailings dam in Brumadinho, MG, and the second is the sinking of the ground in five neighbourhoods in the city of Maceió, AL. Such events generated serious consequences and irreparable socio-environmental impacts. Seeking to understand the public relations strategies that the companies Vale S.A. and Braskem employed when dealing with these crises, this case study helps us think about public relations practices in a country marked by mining tragedies. This paper defends the need to think critically about public relations activity as a right arm of public opinion.