We use a primitive equation Ocean General Circulation Model to simulate theocean circulation regime in the Eastern Weddell Sea. The computer modelROMBAX (Revisited Ocean Model based on Bryan And Cox) is an improved versionof an earlier ocean model, which has been developed to allow the simulationof the flow regime in ice shelf covered regions. The Eastern Weddell IceShelf (EWIS) region is of particular importance because of its narrowcontinental shelf and its location at the inflow of water masses from theeast into the southern Weddell Sea. We have compared the simulated flowpattern and water properties in the EWIS region with the available sparseobservations. While the general observed structure of temperature andsalinity is reproduced, the model tends to overestimate the on-shore flow ofwarm deep waters. This discrepancy is not large enough to seriouslyinfluence the ice shelf - ocean interaction, which is in good agreement withestimates based on field observations. The mean net melt rate is found to be0.88 m yr^{-1} (2.1 mSv) and has a strong seasonal cycle. Sensitivity studieswith different ice shelf configurations (no melting, no ice shelf, closedcavity) show strong impacts on the water mass properties in the EWIS region,with up to 0.7 degC difference in temperature and 0.05 in salinity relative tothe control run. Our results suggest that the EWIS region is of substantialimportance to water mass preconditioning and formation in the Weddell Sea,although no deep or bottom water formation occurs in the eastern Weddell Seadirectly.