Summary Eight Greater Stick-nest Rats (Leporillus conditor S.) were re-introduced into a 8 ha release pen within the Arid Recovery Reserve, South Australia, in September 1998. Their weight, reproductive condition, activity, habitat use and grazing impacts were investigated during the 8 month experimental trial. Greater Stick-nest Rats increased in weight and bred successfully after the end of summer (April 1999). They consumed native vegetation including Bladder Saltbush (Atriplex vesicaria), Ruby Saltbush (Enchylaena tomentosa) and Sturt's Pigface (Gunniopsis quadrifida) but Sturt's Pigface was most heavily browsed and no monitored plants died from over-browsing during the trial. Rats preferred dune habitat and the two largest female rats maintained discrete activity areas and shelter sites. Nocturnal activity of adult male rats was centred around adult females with both sexes generally staying within 150 m of daytime shelter sites. Shelter sites were commonly within dead Umbrella Wattle (Acacia ligulata) or Narrow-leafed Hopbush (Dodonaea viscosa) shrubs covered in low vegetation, and rats also adapted burrows of other species to use as below-ground components. Although supplementary water was provided and may have ensured survival over the hot summer months, the trial release was considered a success and a full-scale re-introduction of the Greater Stick-nest Rat was conducted in 1999.