The most threatened Brazilian ecosystem, i.e. the Atlantic forest, shelters an amazing biodiversity similar to what can be found in the Amazon. Both largest Brazilian top predators, the jaguar (Panthera onca) and the cougar (Puma concolor), occur. The Iguaçu National Park [INP] is the largest Conservation Unit [CU] of Atlantic forest benefiting from federal protection. The park annually welcomes thousands of tourists because of its world-known waterfalls. It therefore represents a unique opportunity to study anthropogenic disturbances over cougars’ behaviour and local communities’ attitude towards large predators. Local data regarding this species are virtually inexistent. This project intends to assess the population status of cougars occurring in the INP area, using passive methods and telemetry monitoring. It will be possible to do a temporal comparison with the results compiled in Crawshaw PhD thesis (1995) conducted in the same area. Our results should also allow a better understanding of ecological dynamics, providing scientifically-grounded recommendations for wildlife management and conservation within this CU.