From available bottom-hole temperatures and conductivities estimated from lithologic descriptions, heat-flow estimates are calculated for 72 sites on the Canadian Atlantic Shelf. The resulting data suggest a pattern of low heat flow (~055 mW/m2) within the Paleozoic basins in proximity to land areas and generally intermediate heat flow (~60–80 mW/m2) along the outer half of the continental shelf. Higher heat flows (~90 mW/m2) are estimated along the shelf edge in some areas, e.g., the southwestern Scotian Shelf and the eastern Newfoundland and Labrador shelves. Radioactive heat generation in sediments that thicken seawards probably does not account for the observed increase in heat flow. The possibility that higher heat flows in some areas may arise because of fluid movement from depth is suggested. Various other causes for the high heat flows, e.g., tectonic or magmatic activity, are considered less likely.