Giraffes (Giraffa camelopardalis) are one of Africa’s most iconic species and their decline in the wild has received extensive media attention with their new IUCN listing as Vulnerable, however their behaviour and social structure in natural environments are surprisingly poorly understood. Social structure results from the patterns of interactions among individuals and influences individuals’ fitness as well as disease transmission, population genetics and dispersal. Understanding changes in individuals’ social relationships through time is essential to inform conservation action plans, as social relationships can affect survival and breeding potential. The social system of giraffes is characterised by high levels of fission-fusion dynamics, where social groups change regularly in size and composition, but non-random connections exist between individuals. Here, we use a unique dataset from Namibia’s Etosha National Park spanning 12 years on 160 individuals with known ages to describe the dynamic nature of giraffes’ social networks. We test the hypothesis that giraffes’ social connections vary with sex and age. We predict that different changes occur between the social environments of males and females as they move from adolescence to sexual maturity. We also expect differences in the longevity of males’ and females’ dyadic relationships. In particular, we predict that females maintain long-term social relationships with others of their age cohort while males’ relationships decrease in strength as they adopt a roaming strategy to find potential mates. This long-term analysis will add to the understanding of social dynamics for the management of giraffes and other long-lived species with fission-fusion social systems.