We examined the effects of protection from human activities and effects of tourist hunting on densities of 21 large mammal species in Tanzania. Aerial censuses revealed that mammal biomass per km2 was highest in National Parks. Densities of nine ungulate species were significantly higher in National Parks and Game Reserves than in areas that permitted settlement; these tended to be the larger species favoured by poachers. The presence of tourist hunters had little positive or negative impact on ungulate densities, even for sought‐after trophy species; limited ground censuses confirmed these results. Our analyses suggest that prohibition of human activity, backed up by on‐site enforcement, maintains ungulate populations at relatively high densities, and challenge the idea that enforcement is only effective when spending is high.