South American montane grasslands are hotspots of biodiversity, characterized by unusually high levels of endemism. They are the birthplace of the massive rivers and watersheds, shaping the geography and biota of the continent and providing water to millions of people. Here, we provide an overview of fire ecology in two megadiverse South American montane grasslands, the Páramo in the Andes and the Campo Rupestre in eastern Brazil. For the Páramo, we discuss ecological and evolutionary aspects of fire ecology with a focus on vegetation, given the apparent lack of knowledge for both animal and microbial communities. For the Campo Rupestre, in addition to a brief discussion on fire effects on vegetation, we also attempt to synthesize fire effects on seed germination, invertebrates, vertebrates and microbial communities. After laying out the state-of-art on fire ecology on montane grasslands, we identify knowledge gaps and suggest research priorities that can enhance our capacity to manage fire sustainably.