In the framework of the major multinational coordinated POEM-II-86 (March–April 1986) and POEM-V-87 (September–October 1987) cruises in the Eastern Mediterranean, high resolution hydrographic (CTD) data were collected by R.V. Aegaio in the eastern Ionian Sea, south Aegean Sea and northwest Levantine Basin. The intercalibrated data sets were analyzed objectively for an optimal estimation of the basin's circulation in two different seasons. The analysis reveals a rather complex general circulation pattern consisting of basin, sub-basin and mesoscale features during both study periods. The major results concern the advection of the Modified Atlantic Water (MAW) along its eastward route, the spreading of the Levantine Intermediate Water (LIW) and its trapping by the eddy fields; the interaction between the south Aegean Sea and the eastern Mediterranean; and the reverse circulation in the Cretan Sea during winter and summer. From the hydrography and the dynamic height maps, synthetic schemes show the main circulation features in the two seasons.