Abstract. The entrainment of buoyant ambient water into the overflow plume of Denmark Strait and the associated downstream warming of the plume are estimated using time series of currents and temperature from moored instrumentation and classical hydrographic data. Warming rates are highest (0.4–0.5 K/100 km) within the first 200 km of the sill, and decrease to 0.05–0.1 K/100 km further downstream. Stirring by mesoscale eddies causes lateral heat fluxes that explain the 0.1 K/100 km warming, but in the first 200 km from the sill also vertical diapycnal fluxes, probably caused by breaking internal waves, must contribute to the entrainment.