Heat flow measurements in 4 deep drill holes near Voisey Bay, Labrador, have yielded the lowest value ever reported in the Canadian Shield, 22 mW m-2. This very reliable estimate is also one of the lowest continental heat flow values world wide. It requires the crust to be very poor in radioelements in this part of the Archean Nain Province. It also strongly supports the view that mantle heat flow is low (<15 mW m-2) throughout the Canadian Shield, with no trend of increasing mantle heat flow near the edges of the continent. It also raises questions about the controlling mechanism for rifting and the opening of the Labrador Sea at 100 Ma. ¿ 2000 American Geophysical Union