Conservation scientists consider the designation of Protected Areas an important strategy to mitigate socio-environmental damages, biodiversity loss and climate change. Significant environmental impacts are caused every year by fires in Amazonia. In this study, we explore the hypothesis that Protected Areas have an inhibitory role on fire occurrence in Acre state. Then we evaluate the patterns of fires occurrence in different management categories and jurisdiction. For this, it was considered buffers of different sizes inside and around the protected areas perimeter. Fire density was calculated for each buffer, and comparisons between inside versus outside were carried out. It is observed that outside Protected Areas fire density is always higher than inside, indicating the presence of inhibitory process by the protected area borders. The results also showed that such inhibitory process does not occur equally among management categories and jurisdiction. Moreover, this study highlights the importance of establishment of buffer zones based on technical studies and considering the importance on protect not only the protected area itself, but also its surroundings.