Five sites were drilled during Ocean Drilling Program (ODP) Leg 149 on the Iberia Abyssal Plain (Fig. 1) to sample the upper crust within the ocean/continent transition of the plain in order to establish its nature and test predictions based on geophysical observations (Whitmarsh et al., 1993). Eocene sediments were recovered using the rotary core barrel from four holes (897C, 897D, 899B, and 900A) among the eight drilled at the five sites. The Eocene section recovered at Site 900 is continuous and considerably expanded because of its relatively shallow-water depth above the continental crust, where it has remained consistently above the carbonate compensation depth (CCD). Sites 897 and 899, situated above the ocean/continent transition, are at a deeper water depth and, therefore, have noncontinuous, relatively short Eocene sections. Nannofossils have proven valuable for dating the Eocene pelagic sediments, although their preservation is normally moderate or poor. Reworking is evident throughout the Eocene sections in each hole. However, the light-colored, hemipelagic and pelagic sediments (Bouma unit Tf) that occupy the uppermost part of turbidite sequences were deposited above the CCD under highly productive waters and provide reliable nannofossil biostratigraphic data. The purpose of this study is to document the calcareous nannofossils from Eocene sediments recovered during Leg 149 and to establish their biostratigraphic framework.