An intensive field experiment was carried out from March 6 to April 30, 1990, in the eastern Alboran Sea to understand the relationship between the large-scale circulation and the location of the transition zone between new and longer-resident Modified Atlantic Water (MAW). The detection bf a strong jet (80 cm s(-1)) of new MAW with anticyclonic curvature near the Morocco coast suggests that the Eastern Alboran Gyre (EAG) was not fully developed. a new state of the circulation in the eastern Alboran basin, intermediate between the EAG (Viudez et al., 1995) and the Lanoix (1974) state, is presented. Also important is that the Almeria-Oran Front was not present in the upper layer, that small-scale instabilities were detected in the northern region, and that significant nongeostrophic flows were observed. All these features are clearly indicative of the high spatial and temporal variability of a region where complex adjustments among density, velocity, and topography occur.Unión Europea (MAS2-CT93-0066) Ministerio Español de Educación y Ciencia (AMB93-1046-CE)Peer reviewed