This work integrates paJeoeco logica1 research data obtained in Campos Basin and others areas of the Brazilian continental margins with those from different regions of the South Atlantic. A general model is proposed for the oceanographic evolution of the South Atlantic in the Mid-Cretaceous. Since the Early-Middle Albian, probably since the Aptian-Albian transition, the area extending from the equatorial region to the São Paulo Plateau-Walvis Ridge complex was simultaneously invaded by waters from the North (Tethys Sea) and South. The sea then formed constituted a long, continuous, and narrow epicontinental sea-way. Its waters were warm , physic-chemically unstable, and probably hypersaline. ln the Late Albian, the South Proto-Atlantic had its salinit y decreased to more normalmarine values. It was after a significant anoxic event in Cenomanian-Turonian times that truly oceanic deposition phase started.Resumo indisponível.