An average geothermal gradient of 25 + or - 5 mK/m and an average heat flow of 46 + or - 5 mW/m 2 have been determined for 16 out of 20 analyzed wells along a profile across the Sverdrup Basin in the Canadian Arctic. These estimates, based on deep bottom-hole temperature (BHT) data from exploration wells and the permafrost base boundary temperature, together with assumed heat conductivities from net rock analysis, are surprisingly low and disagree with previously published results based on shallow data. The differences may be due to the dramatic changes in boundary temperature conditions from moderate subsea conditions to ground-surface low temperatures as a result of marine regression. Because of these effects, it appears that deep BHT temperature data are valuable in providing information about the deep heat flow. The heat flows thus determined indicate that the basin has approached thermal equilibrium.