To obtain data on home range, movements, activity and habitat use by giant anteaters Myrmecophaga tridactyla, seven animals were captured, radio-collared and monitored from March to December 2001 in a 104-km2 study area in the Pantanal wetland, Brazil. Four of five males used areas that covered 4.0–7.5 km2 (5.7±1.7 km2), and one of two females monitored occupied a larger area (11.9 km2) than the males, but none of the curves of cumulative area unequivocally reached the asymptote. Generally, there was considerable overlap among individual areas used. The home-range estimates were calculated using the 100% minimum convex polygon, and 95% adaptive kernel methods. The areas used by the giant anteaters in the Pantanal wetland were larger than home ranges of giant anteaters in the Serra da Canastra National Park, Brazil. The habitat types were generally used in the same order as they occurred in each home range. Two giant anteaters previously monitored with VHF radio-telemetry were subsequently tracked with a modified global positioning (GPS) system in different periods. The modified GPS acquired data on activity and habitat use for c. 9 days. Giant anteaters did not show a similar pattern of habitat use during the period of study using the modified GPS unit, but their activity patterns were similar. One of the ranges recorded over 9 days with this method was larger than the range obtained over 252 days by standard VHF radio-telemetry.