A group of scientists and students protested in favour of animal testing in Oxford on Saturday.
The marchers wanted work to re-start on a new animal testing research centre in the city which stopped after threats from animal rights protestors.
The march was set up by Pro-Test, who say that animal tests are an important part of scientific research.
But other protestors took to the streets at the same time, to speak out against the research centre.
But some animal rights groups have warned that students who joined the protest in favour of testing might be in danger.
Robin Webb, of the Animal Liberation Front, said some activists might see students as targets after the protests.
Animal rights activists have threatened people linked with animal testing in the past, and many people view Britain as a dangerous place for scientists working on animals.