In the Bolivian Chaco the red tegu lizard Tupinambis rufescens is the most important reptile among indigenous communities for subsistence, commercial and traditional medicinal purposes. Information on the home range and habits of Tupinambis rufescens in an area free from hunting pressure is an important basis for a management plan for this species in the Chaco, to ensure that commercial hunting programs will not threaten the species' long-term survival in the region. We used surgically implanted radio transmitters (nine individuals) and temperature dataloggers (five individuals) over a two-year period to describe home ranges, burrow use, as well as daily and seasonal activity patterns at a field camp next to the Kaa-Iya del Gran Chaco National Park. Red tegus occupy home ranges of 16–54 ha, with maximum distances travelled of 700–1500 m. In order to survive the strongly seasonal climate of the dry Chaco they strictly limit their daily and seasonal activity, and rely heavily on burrows. They are diurnal, with an activity peak from 11:00–12:00 h. Their activity period is September—April, with some variation among individuals and among years. They remain inactive in a single underground burrow during the May—August estivation months, and use multiple burrows and shelters for nighttime refuges during the active months. The dataloggers provide extremely detailed body temperature information describing daily and seasonal activity patterns, but surgical implantation should be undertaken by specialized veterinarians.