Trophy hunting and ecotourism are important forms of sustainable utilisation in the human-impacted, working landscapes outside of formal parks and reserves. Research on the sustainability of such tourism operations, however, has focused on the financial viability of tourism operators, rather than environmental effects. This paper examines the sustainability strength of wildlife utilisation on private rangelands in Namibia in terms of ecological impact. Using grounded theory, 43 members of commercial conservancies were surveyed to identify themes in the practice and perception of sustainable utilisation. While basic tourism was infrequent, trophy hunting was a common source of revenue from wildlife. Three emergent themes from the data included differences in tourist versus hunting operations; attitudes and perceptions of the administration of conservation efforts; and the co-management of livestock and wildlife, especially farm economics and game-proof fencing. Overall, increases in the proportion of income derived from game (above 20% of farm revenue) were associated with concurrent reductions in domestic livestock, but did not increase the use of game-proof fences. Other factors delineating "weak" and "strong" sustainability on commercial Namibian rangelands are discussed. Keywords: ecotourism, game farming, game ranching, safari hunting, sustainable utilisation, trophy hunting.