The importance of the Kuiseb river as a linear oasis for larger mammals in the Namib desert, Namibia, was investigated over a period of three years. Following seasonal flooding the river dries rapidly confining consumable water to irregularly spaced pools which decrease in number and surface area as the dry season progresses. Compared to the lower sections of the river more water and less vegetation are available in the relatively inaccessible upper parts of the canyon, and vice versa. Based on direct observations and tracks at waterholes more mammals visit the lower than the upper sections of the river. Indications are that the pronounced seasonal influx of gemsbok Oryx gazella into the riverbed, presumably from the surrounding dune fields, is primarily dictated by the availability of water. The riverine habitat of the Kuiseb is therefore a resource critical to the survival of at least part of the central Namib ungulate population. Keywords: Kuiseb, larger mammals, Namib desert, water.