A semiquantitative X-ray diffraction study of the finer-than-2μ-size fraction of the surface sediments of the eastern Mediterranean Sea has been carried out. On the basis of the abundances and the distributional patterns of the different clay minerals six mineral assemblages are distinguished. These assemblages have distinctive sources and their dispersal reflects different agents of transport in the eastern Mediterranean Sea. A Nile assemblage with very high amounts of well-crystallized smectite (> 50%) and 15–25% kaolinite is found on the eastern Nile cone and within the eastern Levantine Basin. Its distribution has resulted from the dispersal by the easterly directed surface water currents which form part of the counter-clockwise gyre in the eastern Mediterranean Sea. The Levantine intermediate water has transported from the southeast Aegean Sea on to the Mediterranean ridge southeast of Crete a southeast Aegean assemblage characterized by 40–60% well-crystallized smectite and higher contents of chlorite and illite than in the Nile assemblage. A kaolinite-rich assemblage (20%– > 30% kaolinite), coinciding with high carbonate values, occurs on the western section of the Mediterranean ridge and to some extent in the western Nile cone, as a consequence of transport by wind from North Africa. The restriction of Kithira and Messina assemblages (illite- and chlorite-rich assemblages) to deep parts of the Ionian Basin is chiefly due to water movements involved in deep circulation. A Sicilian assemblage with 20– > 30% kaolinite and 30–50% smectite in the westernmost part of the Ionian Basin south of Sicily, has mainly resulted from the dispersal by easterly moving surface waters from the western Mediterranean Sea.