This paper summarizes the magnetostratigraphic and biostratigraphic results obtained with siliceous microfossils (diatoms, radiolarians, silicoflagellates) on Neogene sections recovered in the Weddell Sea (Antarctic Ocean) during Ocean Drilling Program Leg 113 (Sites, 689, 690, 693, 694, 695, 696, and 697). The biostratigraphic studies resulted in the establishment of an improved and revised Neigene biosiliceous zonation for the Antarctic Ocean. The zones are calibrated directly to the geomagnetic time scale. This is the first attempt at direct calibration of Miocene Antarctic biostratigraphic zones with the geomagnetic time scale.