This paper analyzes the demographic responses of the large slaver land holders of Rio de Janeiro, to the British pressure to end slavery in the Atlantic Ocean. It places special emphasis on the decades of 1810 and 1820, although it covers a longer period in lesser detail. The article questions the idea, widely disseminated in Brazilian historiography, that the internal slave trade in Brazil was enough to respond to the demands of growing slaver plantations and, therefore, that the natural positive growth of the slave population and of slavery were incompatible variables in colonial and imperial Brazil.