Ground transects were used to determine densities of 24 larger mammals in Katavi National Park. The Park consists of miombo woodland habitat and two seasonal lakes. Mammalian biomass was extremely high due primarily to large numbers of buffalo. The highest mammal densities were found around Lake Chada to the southeast of the Park. Contrary to earlier reports, species’ densities did not differ signiﬁcantly between dry, wet and intermediate seasons, suggesting that, aside from elephant and warthog, mammals did not enter or leave the Park in large numbers. Similarly, aside from zebra and waterbuck, sightings of species in diﬀerent vegetation types did not change markedly between seasons. Thus, seasonal lakes in Katavi National Park support very high local concentrations rather than acting as dry season refuges for mammals outside the Park.