Historically, peregrine falcons (Falco peregrinus anatum/tundrius) nesting in southern Québec used natural cliffs, but they now use a range of sites, including rock faces in industrial quarries. There are no recent studies that specifically describe natural nest sites in this part of the province, and no studies that compare natural cliff nest sites with those found on quarry rock faces. Using information from photographs and field observations, we compared the characteristics of nest sites in 25 quarries and at 39 natural sites occupied between 1995 and 2013. One third of the nests in both site types were in old common raven (Corvus corax) nests. Quarry sites and natural cliff sites differed in their orientation, with the former generally facing north/northwest and the latter, south. Quarry sites also had less shrub and tree cover, and nest platforms were located higher on the rock face. Furthermore, a lower proportion of the nest platforms in quarries were protected by rock overhangs, and they were closer to open water bodies. The biological importance of these differences for breeding peregrine falcons is discussed.