The sea ice model developed by Hibler <1979> is coupled with the ocean general circulation model developed by Bryan <1969> and Cox <1984> to examine the seasonal ice cover over the Labrador Shelf as well as dynamic and thermodynamic roles of the shelf/slope water. The model covers the area between 40 ¿N and 65 ¿N, extends nearly to the European coast, and has realistic bottom topography. The model is initialized with the temperature and salinity compiled by Levitus <1982>, with fresh and cold shelf water imbedded, and then forced by observed atmospheric data. Simulation is first carried out for individual ice seasons, i.e., 1970/1971 season for 6 months from December 1, 1970. Several case runs are carried out with uncertain parameters varied within their possible ranges. Interannual variabilities are examined in additional simulations for the 1968/1969 and 1971/1972 seasons. General characteristics of the seasonal ice growth and decay are duplicated in the model. However, some discrepancies are observed in the 1970/1971 simulation, including the maximum ice cover about 20 days earlier in the model than in the observation. The earlier start of ice decay is related to a rapid ice melting in March, which could be reduced by increasing water albedo. This modification is justified, because thin ice is forced to merge immediately with thick ice in the present two-category ice model. Heat flux to the shelf area due to advection of the warm offshore water induces long-term warming effects and is also responsible for the excess of ice decay in spring. The interannual variability among the light, medium and heavy ice seasons is well reproduced in the three runs for the 1968/1969, 1970/1971 and 1971/1972 seasons, respectively. The ice-cover variability is related to that in the air-sea heat flux. However, a major part of the heat flux variability is retained in the water, while the ice cover absorbs a minor part. The timing variability among the three seasons is duplicated in the simulations as well. ¿ American Geophysical Union 1996