The spatial organization of the endangered Iberian lynx, Lynx pardinus (Temminck, 1827), was studied in Doñana National Park, south-western Spain, between 1983 and 1992. Thirty-six individuals (19 males and 17 females), including 24 adults (13 males and 11 females) were radio-tracked, providing 13,950 locations during 17,111 radio-tracking days. Iberian lynxes were essentially solitary (95.9% of simultaneous locations apart) and interactions were restricted to rearing activities by females. Adult associations were uncommon. Seasonal (four months) home ranges were larger for adult resident males (10.3 ± 1.9 km2; n= 5) than for females (8.7 ± 2.4 km2; n= 5). Lynxes used a central portion of the home range intensively (‘core area’, 50% Harmonic Mean) with similar size for males (3.7 ± 0.7 km2) and females (3.2 ± 0.8 km2), representing, on average, a 37.6 ± 1.5% and 36.6 ± 4.5% of male and female home ranges, respectively. Intrasexual home-range overlap was usually low between same-sex neighbours (15.1 ± 6.6% males and 22.1 ± 3.3% for females), but some instances of high overlap (>25%), both among males and females, were recorded, corresponding to spatial interactions between neighbours which usually ended with the displacement of one of the contenders. Core areas were mainly exclusive except during these spatial interactions. Actual fights resulting from these interactions seem more frequent than previously reported for other medium-sized solitary felids, likely promoted by high competition for optimum territories due to saturation of the population. The Iberian lynx spatial organization in Doñana works as a land tenure system, as described for other solitary felids. Although the mating system tends to monogamy, with male home range overlapping mainly that of one female, individual variations to polygyny were also found.