Parameters that influence the hunting success of lions in a semi-arid region in Namibia were assessed by means of generalized linear models. Results indicate that when combined, hunting techniques employed by lionesses, lioness group size, prey species, time of day (day/night), terrain, and the interaction between terrain and day/night had significant independent effects on the probabiliry that a hunt would be successful. Hunts that involved co-ordinated stalking were more likely to succeed than other hunt categories. Success of hunting the five major prey species increased linearly with lioness group size. Lionesses were also more successful during hunts on moonless nights in undulating terrain. Under the semi-arid conditions in Namibia, where lions are exposed to eight months of food scarciry in an open habitat, group hunting and co-ordinated co-operation are the most important variables influencing the outcome of hunts and therefore also per capita food intake. In this environment group hunting may be an important factor in the evolution of socialiry in the species.