The heat balance deduced from a three-dimensional, seasonally driven primitive equation model of the North Atlantic is described and compared with observations. The greatest response to the seasonal forcing occurs in the region between ~5 ¿N and 10 ¿N, where the northward heat transport goes from a minimum of 1.4¿1015 W in the winter, when the Brazil Current and northward Ekman transport are at a maximum. Elsewhere in the tropics and subtropics the range in transport is smaller. In the northern hemisphere (~12¿ to 32 ¿N), there is a significant semi-annual component due to the Ekman transport. The large seasonal changes in heat storage in the tropics are caused primarily by transport divergence rather than surface heat flux. In the annual mean, the equatorial region has a large surface heat flux gain associated primarily with the conversion of ~6¿106 m3 s-1 of northward geostrophic flow with &thgr;<20 ¿C in the southern hemisphere, to a surface Ekman flow with &thgr;~27 ¿C in the northern hemisphere. The seasonal variation in heat storage within the subtropical and subpolar gyres is due almost entirely to the surface heat flux. However, seasonal variations in Ekman transport do lead to a relatively large annual cycle in northward heat transport (e.g., 0.5¿1015 W to 0.9¿1015 W at ~35 ¿N), with maximum transport occurring during the summer when the southward Ekman transport is at a minimum. A comparison of the model results with heat storage estimates shows that the model and data agree very well in the tropics but that at higher latitudes the model underestimates the seasonal variations because of inadequate vertical penetration of heating during periods of warming.