The spatial resources used by a population of lace monitors (Varanus varius) were examined over an active season (September–April) and an inactive season (May–August). In total, 33 monitors were observed, of which 23 monitors were radio-tracked for up to 11 months. Radio tracking provided new information on the spatial ecology of V. varius. During summer (December–February), V. varius moved often, over large (184.5 ha) overlapping home-range areas. In the intermediate seasons of spring (September–November) and autumn (March–May), monitors moved less often and used less than 39% of the summer home-range. Finally, in the cold winter season (June–August) many monitors did not move at all and most used less than 5% of their summer home-ranges. The thermal environment, and reproductive status of V. varius affected its use of space, and the importance of these factors varied seasonally. No spatial segregation was noted between monitors, with home-ranges overlapping on average for eight other radio-tracked monitors. The home-range size of V. varius was accurately predicted using published data on body mass and home-range size for the Varanidae.