A primitive equation model is used to investigate the role of winter intermediate waters in the surface circulation of the Balearic Sea in spring-summer. The interior solution is forced by restoring to thermohaline fields in four reservoirs schematizing the adjacent basins. Several simulations are carried out with different initial and boundary conditions, which evidence the sensitivity of the circulation to the thermohaline structure in the basin and to the inflows through the channels. The accumulation of winter intermediate waters to the north of the Ibiza Channel in spring is found to have a drastic effect on the circulation and on the water exchange through the channels: the Continental Current is deflected away from the slope toward the Balearic Islands, hence reducing the southward transport through the Ibiza Channel while enhancing the transport through the Mallorca Channel. A simultaneous northward energetic inflow of modified Atlantic waters through the Balearic Channels happens to amplify this effect and can lead to a major blocking of the Continental Current, which veers back to the north, feeding the Balearic Current during several months. Model results compare favorably with observations and help interpret some data sets. ¿ 1999 American Geophysical Union