To investigate the movement patterns and activity of Hydromedusa maximiliani in southeastern Brazil, sixteen adult freshwater turtles (eight males and eight females) were monitored with radio-transmitters from October 2009 to November 2010. An additional 22 turtles (11 males and 11 females) were monitored with thread-bobbins over a 3-day period. Hydromedusa maximiliani showed strong tendency to remain close to the river course. The distance moved each day varied from 0 to 179 m/day (radio-tracking) and 1.5 to 201 m/day (thread-bobbins). Males moved greater distances than females during the mating season (August to November), while females exhibited pronounced movements associated with egg-laying (December to February).Male and female movements did not differ significantly. Straight line distancemeasurements, usually obtained by radio-tracking, underestimate actual movement distances, since the nonlinearity of movements is not captured by radio-tracking as opposed to spool tracking, even when long distances are travelled. Results from this study are important for establishing conservation strategies for this vulnerable species.