The Prats de Molló bone festival, also called El Dia dels Ossos, is a festival that takes place annually in late winter in the town of Prats de Molló (municipality of Prats de Molló and la Presta), in the region of Vallespir, Northern Catalonia.

The bone festivals of Prats de Molló, along with those of the Vallespirane municipalities of Arles and Sant Llorenç de Cerdans are the only ones that are still celebrated in their entirety throughout the Pyrenees. They follow each other on three non-coinciding Sundays, following the festival of Candlemas (February 2). In Pyrenean mythology, this date marks the departure of the brown bone from hibernation and the beginning of the end of winter.

The three festivals of the Alt Vallespir bone are registered in the Inventory of the intangible cultural heritage of France. In 2021, these celebrations were canceled due to the high epidemiological rates of the Covid-19 pandemic. Prats de Molló was twinned with the town of La Mata, a municipality in the north of the Valencian Country (ports region) where the Onso de la Mata festival takes place.