Precision temperature measurements have been made in some 150 deep wells and holes drilled in the course of natural resource exploration in the permafrost regions of Northern Canada. In most cases, holes were logged by lowering a probe containing a regions of Northern Canada. In most cases, holes were logged by lowering a probe containing a thermistor incrementally down the well, in other cases multi-thermistor cables were left in the holes and periodic measurements taken. In the 1990's, a few holes were logged by a automatic quasi- continuous logging system. Most holes were logged annually for 5-10 years after drilling completion, and measured temperatures show the disturbance due to drilling and the gradual recovery to near-undisturbed conditions. Some holes in the collection are of depth less than 125 m. Permafrost thicknesses are estimated at each well or hole from the depth of the 0 degree Celsius isotherm. This data collection provides the highest quality of permafrost temperature and permafrost thickness information available for Northern Canada. Other data are the large number of downhole temperature and permafrost thickness estimates taken during commercial well logging of petroleum exploration wells, and are by nature of lesser quality. These data are not included in this data set, but references to compilations of this data are provided. A short text (2000 words), tables of site locations and permafrost thicknesses with small-scale maps, and an extensive bibliography accompany the data collection. The file structure and contents of each file are well described. The text is sufficient to locate the data of interest, and the file description is adequate for a user to recover the parameters of interest. The data are presented on the CAPS Version 1.0 CD-ROM, June 1998.