Petroleum Systems of the Chacoparaná Basin, Argentina The Chacoparaná basin is a large intracratonic basin, ellipticaly shaped with NNE orientation. This basin originated from a Proterozoic rifting event and developed throughout the Paleozoic mainly as a consequence of deep intracratonic thermal processes and the influence of the active southwestern margin of Gondwana, resulting in a compartmentalized basin with different depocentres. Petroleum exploration during the twentieth century resulted in 37.000 km of seismic coverage and 36 wells drilled. This contribution presents a summary of the basin geology, the petroleum systems analysis and the evaluation of the unconventional shale reservoirs potential presence. This study conclude, despite of the fact there are large areas of the Chacoparaná basin without direct subsurface data, that according to the available information and this petroleum systems evaluation, the source rocks properties arise as the critical play element, which not yet proved of having generated and expelled significant hydrocarbon volumes. As unconventional shale reservoirs, none of the known source rocks meet such condition.