Perimeter fencing prevents dispersal of kangaroos from golf courses and some nature reserves around Perth, Western Australia, leading to overpopulation and culling. We investigated efficacy and behavioural effects of chemical fertility control with deslorelin as a more attractive option. In October 2007, we sedated 12/23 female western grey kangaroos (Macropus fuilginosus ocydromus) on Melville Glades Golf Course, in the Perth suburb of Leeming, 14 km south-south east of Perth city centre, with Zoletil® (8 mg/kg) and injected a 4.7 mg depot formulation of the gonadotrophin releasing hormone super-agonist, deslorelin (Suprelorin®), subcutaneously between the shoulder blades (DEC Licence to Take Fauna for Scientific Purposes SF006081, University of Western Australia Animal Ethics approval RA/3/100/592). All 23 kangaroos had young-at-foot and pouch young at the time of treatment. We then recorded the location of all kangaroos on the golf course and the composition of their group, scored their activity when first seen (resting = 0, standing = 1, feeding, travelling, courting, or mating = 2) and presence of obvious pouch young, twice weekly until December 2008. Diurnal home ranges, estimated by minimum convex polygon (mean/SD treated 30.3/10.25 ha, untreated 27.1/8.46 ha) and modified minimum area (mean/SD treated 15.52/3.97 ha, untreated 13.88/5.2 ha) methods showed no significant difference. Treated and untreated kangaroos continued to associate and showed no significant difference in activity (mean/SD treated 0.92/0.14, untreated 0.90/0.15). One treated female disappeared in November 2007 and a new untreated female appeared in February 2008. All 23 carried their pouch young normally through to pouch emergence in summer 2007/8. 3/11 treated kangaroos were seen to mate during the observation period but none produced a new pouch young in 2008, whereas all 12 untreated females did. We conclude that Suprelorin® can be used to manage isolated populations of western grey kangaroos with no serious behavioural effects.