Summarizes some geologic results of the program of oil exploration in three sedimentary basins of Uruguay. The eastern basin contains sedimentary formations of mid-Tertiary to Recent age overlying crystalline basement or Precambrian? volcanic rocks. The northeast basin is composed mainly of upper Carboniferous and lower Permian Gondwana continental and marine epicontinental deposits, underlain by lower Devonian marine beds. The northwest basin is mantled by extensive basalt flows of the upper part of the Gondwana sequence, and geophysical surveying to gain information on lava thicknesses and structure of the underlying sedimentary rocks is in progress.