The isotopic composition of neodymium in the water column of the eastern North Atlantic near the Strait of Gibraltar has been determined for several depths. The data show that the Mediterranean outflow results in a significant shift in &egr;Nd(0) toward more radiogenic values of 143Nd/144Nd in the water column at a 1000-m depth. This corresponds to a depth in the neighborhood of the salinity maximum associated with the Mediterranean outflow. The core of the Mediterranean outflow gives &egr;Nd(0)=-9.8, as compared to &egr;Nd(0)≈-12 in overlying and underlying waters, demonstrating that the Mediterranean waters are distinct from the Atlantic. From mixing considerations we estimate that pure Mediterranean waters have &egr;Nd(0)≈-6. Possible sources of this relatively radiogenic Nd could be from drainage of young continental terranes or the injection of remobilized Nd from deep-sea sediments that have a young radiogenic volcanic component. New data from a depth profile in the western Atlantic is presented. Comparison of Nd data for the eastern North Atlantic with that for the western North Atlantic shows fundamental differences in the water column structures for &egr;Nd(0). While both regions show a pronounced maximum in &egr;Nd(0), the western basin maximum occurs at the near surface rather than at 1000 m. In addition, deep waters of the eastern basin are found to be more radiogenic than the western basin. These differences indicate several sources of isotopically distinct Nd in the North Atlantic. The deep waters of the North Atlantic (>1000 m) have the lowest values of &egr;Nd(0) measured in the oceans. We believe that the source of these low &egr;Nd(0) values, which we associate with North Atlantic deep water, is either from freshwater drainage off the Precambrian shields of North America and Asia into the Arctic Ocean or from the injection of ''older,'' continentally derived REE from deep-sea sediments. Sm and Nd concentrations re found to increase with depth and &egr;Nd(0) changes with depth, indicating both vertical and lateral transport processes from different sources. This suggests a surface source of Nd and injection of REE into the water column from deep-sea sediments or large-scale bottom currents with high REE concentrations.