The thermal resistance (or Bullard) method is used to judge the utility of petroleum well bottom-hole temperature data in determining surface heat flow and subsurface temperature patterns in a sedimentary basin. Thermal resistance, defined as the quotient of a depth parameter z and thermal conductivity k, governs subsurface temperatures B. In practice, bottom-hole and surface temperatures are combined with a measured or estimated thermal conductivity profile to determine the surface heat flow q 0 which, in turn, is used for all consequent subsurface temperature computations. The method has been applied to the Tertiary Uinta Basin, northeastern Utah. Average geothermal gradient and heat flow for the Uinta Basin are 25 degrees C km (super -1) and 57 mW/m 2 , respectively. Heat flow appears to decrease systematically from 65 to 40 mWm (super -2) from the Duchesne River northward toward the south flank of the Uinta Mountains. This decrease may be the result of refraction of heat into the highly conductive quartzose Precambrian Uinta Mountain Group. More likely, however, it is related to groundwater recharge in late Paleozoic and Mesozoic sandstone and limestone beds that flank the south side of the Uintas. Heat flow values determined for the southeast portion of the basin show some scatter about a mean value of 64 mWm (super -2) but no systematic variation.--Modified journal abstract.