Animal abundance is a key measure in conservation and management and tightly linked to population demographics. Demographic data from remote regions, however, are often scarce. Here, we present long-term (1996-2013) demographics on the muskox Ovibos moschatus population at Zackenberg in northeast Greenland. We examine both the inter- and intra-annual patterns in demographic parameters and relate these to environmental conditions. The sex and age composition of muskox groups changed during the study period, and changes were particularly evident in the increasing versus the decreasing phase of muskox abundance. The seasonal pattern of muskox density and group size was a parallel increase from late winter to autumn, which peaked at high densities (approximately seven individuals per km2) in the autumn. The composition of muskox groups also changed between seasons. Across years, the muskox population dynamics was mainly driven by spring snow cover (an indicator of winter conditions), which primarily impacted the calf and yearling recruitments. This relationship, however, appeared to have a temporary decoupling, which may be attributable to pathogens. Our study provides rare insight into the long-term demographics of a remote ungulate population in relation to drivers of change and thus aids the development of adequate monitoring and management plans for muskoxen in a changing Arctic.