We investigated age-specific variation in survival of dominant individuals in a long-lived and monogamous mammal, the alpine marmot (Marmota marmota), from a large dataset collected during a 24-year intensive monitoring of a free-ranging population. We found evidence of actuarial senescence in dominant individuals for both sexes. Survivorship was constant with age until dominant marmots were between 6 and 8 years of age and declined markedly thereafter. No between sex differences occurred in the intensity of actuarial senescence, which might be related to the weak intensity of sexual selection in this socially monogamous mammal. More investigations are needed to know whether cooperative breeding, hibernation, and monogamy, which are key features of the alpine marmot life history, could have shaped the patterns of actuarial senescence we report.