To explore the extent to which ocean mixed-layer dynamics influences dimethyl sulfide (DMS) sea-to-air flux at high latitudes, a model of DMS ocean mixing, biological production, and sea-to-air flux was developed. This biophysical one-dimensional model is driven by meteorology. The model simulates DMS seawater concentrations and vertical distributions, and DMS sea-to-air flux for Prince William Sound and the Gulf of Alaska, from early March through December. Sensitivity analyses revealed that DMS sea-to-air flux is most affected by the rates of flagellate production, zooplankton grazing, photooxidation, and microbial consumption of DMS. Model results show that under conditions of substantial vertical mixing, such as high wind stress or convective mixing, DMS sea-to-air flux increases significantly. At high latitudes these events may coincide with wind-driven mixing or the overturning of surface seawater due to decreasing sea surface temperatures in the autumn. Parameterizations used to estimate emissions of such a highly variable gas as dimethyl sulfide need to include ocean mixed-layer dynamics. The current model is limited by the small number of DMS loss and production rate measurements available. The measurements that do exist have large ranges and come almost exclusively from low and midlatitude regions, mostly during the summer months under calm conditions. Field measurements are needed from high-latitude systems to refine this model, making it an effective tool for designing field campaigns, improving the accuracy of DMS sea-to-air flux estimations, and assessing the contribution of northern oceans to the atmospheric sulfur budget. ¿ 2000 American Geophysical Union