Hundreds of animal rights activists took part in a "Running of the Nudes" Thursday to protest the traditional running of the bulls ceremony in the Spanish town of Pamplona.
The demonstrators ran stripped to their underwear and sporting plastic horns, as well as the traditional red bandana worn by those who take part in the famous Spanish event.
The running of the bulls involves the release of bulls every morning into the streets of the city in northeast Spain.
Daredevil revellers, including many foreigners, run ahead of the stampeding bulls as they are herded down the narrow streets towards the city's bull ring.
Runners are sometimes caught and either gored or trampled by the running bulls and 14 people have been killed in the event since 1911.
The bulls that run in the morning are used in bullfights the same evening.
Thursday's protest was organised by the animal rights group PETA (People for the Ethical Treatment of Animals), which said people from more than 30 countries took part.
Thousands of tourists are expected to attend the week-long festival of the bulls, which starts on Friday.
The running of the bulls was immortalised in Ernest Hemingway's 1926 novel "The Sun Also Rises".