We investigated site fidelity of territorial male guanacos (Lama guanicoe) in Torres del Paine National Park, Chile. The study took place over a 10-year period, with intensive work in the final years, 1997–1999. Guanacos have a social system of resource-defense polygyny with fluid movement of females between male territories. After the annual winter migration, males establish and maintain their territories from mid-spring until late autumn. Territorial males are classified as solo or family-group territorial males. We collected data on type, location, size, and usage of territories for tagged, known-age males. We compared male territorial fidelity between mating (8 December–11 January) and nonmating periods within the 6-month territorial season each year (1 October–15 March) and between multiple years. Males used the same area within the 1997 and 1998 territorial seasons (n = 47). Most males (73%; n = 60) also returned to the same territory location from year to year. Males (27%) that shifted territorial locations showed no clear patterns in changes between solo territorial males and family-group territorial males. High predictability of male territory sites within a given year and between years has short- and long-term benefits for management and conservation efforts.