We estimated home range size and overlap and activity patterns of ocelots in a protected subtropical forest, the Iguaçu National Park (INP), in southwestern Brazil using a long-term dataset from 1990 to 2001. We expected that male ocelots would have larger home ranges than females and that ocelots would be primarily nocturnal. In general, we found large home ranges sizes, with male home ranges larger than females, and significant intra and intersexual overlap. In addition, ocelots were more active during crepuscular hours. The observed larger home ranges than in other sites and significant overlap observed may reflect weak territoriality of ocelots in our study. The activity patterns observed may reflect an increase in the consumption of more diurnal and crepuscular prey species, such as lizards and agoutis. The weak territoriality and more crepuscular activity patterns may be indicatives of the flexibility of this felid species’ ecology.