We studied the home-range and core-area size and overlap of Tehuantepec jackrabbits (Lepus flavigularis) by radiotracking 32 individuals between May 2001 and April 2003 in savanna habitat in the Isthmus of Tehuantepec, Oaxaca, Mexico. Annual home-range and core-area sizes averaged 55 ha ± 8 SE and 8 ± 1 ha for 10 adults of both sexes using the 95% and 50% fixed-kernel isopleths, respectively. Seasonal home ranges varied widely for adults, from 15 to 111 ha for females and from 24 to 166 ha for males. Juvenile males had larger seasonal home ranges than did juvenile females (X̄ = 80 and 24 ha). For adult jackrabbits, seasonal home ranges were larger during the 1st year compared to those of the 2nd year of study (X̄ = 87 and 49 ha), particularly for females. Home ranges and core areas of Tehuantepec jackrabbits were comparable in size and overlapped between active periods (nocturnal and crepuscular hours) and inactive periods (diurnal hours). Adults overlapped their home ranges with 1–10 individuals. Home-range overlap among females was greater than among males. Females shared portions of their ranges with other females more frequently than did males with other males. Home-range and overlap analysis suggests that Tehuantepec jackrabbits have polygamous mating behavior and nonterritorial social organization.