A stream function projection of historical hydrographic data is applied to study the heat flux problem in the Antarctic Circumpolar Current (ACC). The ACC is defined as a circumpolar band consisting of mean streamlines passing through Drake Passage. Its mean path exhibits a globally meandering pattern. The calculation of zonal heat transport shows that the ACC warms along its equatorward segments (South Atlantic and Indian Ocean) and cools along its poleward segment (South Pacific). The primary heat sources for the ACC system are two western boundary currents, the Brazil Current and the Agulhas Current. The mean baroclinic flow relative to 3000 dbar carries 0.14 PW poleward heat flux across 56¿S and 0.08 PW across 60¿S.