Wolf–ungulate interactions were studied in a mountainous region of the western Alps (Italy) from December 1999 to November 2002. Analysis of 848 scats of wolves Canis lupus showed that their most important prey was wild ungulates (87.2%). Cervids were the preferred prey (74.2%) and constituted predominant food items both in winter (84.2%) and summer (54.3%). Wolves preyed most intensively upon young ungulates. Presence of domestic ungulates on high-altitude pastures during summer (May–October) influenced wolf diet (summer 19.0%, winter 0.3%), but, despite the major density of domestic livestock, wolves still preferred wild ungulates. A strong trophic relationship between wolves and red deer Cervus elaphus emerged from the present study. During three winters, 177 ungulate carcasses were recorded. Excluding hunting, the most important cause of death in red deer was predation by wolves (51.5%), followed by disease and starvation (36.4%) and traffic accidents (12.1%). The majority of red deer killed were hinds (58.8%) and calves (29.4%); stag kills represented only 11.8%. For roe deer Capreolus capreolus, starvation and diseases were the lowest factor (11.5%), slightly higher than wolf predation (10.8%), while traffic accidents were the main cause of mortality (77.7%). Chamois Rupicapra rupicapra seemed to be less important than red deer and roe deer in the diet of wolves. The high susceptibility of red deer to wolf predation could be a result of the strong overlap of habitat and altitude use with the wolf, and to their more conspicuous herding.