Medical research involving animals is "essential", a spokesman for a student group backing Oxford University's £18m biomedical research lab says.
Members of student group PRO- Test gathering in Broad Street
Ian Simpson, of PRO-test, due to march with staff in Oxford in support of the facility under construction, says he hopes students will not be targeted.
Alistair Currie, of the British Union for the Abolition of Vivisection, said using animals "belongs in the past".
The event coincides with animal rights group Speak's rally opposing the lab.
Last week, Robin Webb, the Animal Liberation Front's spokesman, said student accommodation could be targeted and some activists might "perceive" student groups supporting animal testing as "legitimate" targets.
Mr Webb said it was "unlikely" students themselves would be targeted as a result of Saturday's Pro-Test rally.
Mr Simpson added: "Basically we want to get out there and try and make the point that at the moment medical research involving animals is essential if medical science is to move forward.
"Obviously, we hope we won't be targets. We are out there to try and make an entirely peaceful protest and get our message across.
"Certain proteins are found in both humans and animals and if you are interested in what you can do with those proteins to cure diseases, this is the most effective way to do it at the moment."
But Mr Currie said experimenting on animals "is something neither morally nor scientifically justifiable".
"It is not a productive, effective or safe way of generating new medicine or doing research," he explained.
Pro-Test founder Laurie Pycroft explained on BBC's TODAY programme why he is making a stand.
The 16-year-old said: "I have always believed very firmly in science.
Students who support animal experiments march through Oxford
"I am a rather logical person and I think it is about time the medical and scientific community in general was stood up for.
"The argument has been pretty much one-sided from a minority of the population and we are just speaking up for the silent majority."
Saturday's student demonstration, whose speakers include Dr Evan Harris MP, the Liberal Democrats science spokesman, begins on Broad Street in Oxford.
Supporters will then march on to the laboratory building site in South Parks Road.
The rally is also expected to hear arguments from leading academics at the university.
Thames Valley Police said it had met Pro-Test organisers but not Speak organisers despite trying to make contact with representatives.
Robert Cogswell, of Speak, which opposes violent protest, said that the group had decided not to "enter into dialogue" with the police after what he described as "disgraceful" tactics at an earlier Speak rally in Oxford city centre.
Five people were arrested for public order offences at last month's demonstration.
On Saturday, Speak has planned a main demonstration in Cornmarket Street, while the Pro-Test march makes its way to the lab site nearby.
Oxford University resumed building work on its new laboratory complex last November after work was halted in July 2004 following a sustained campaign of protest from animal rights groups.
A new, unnamed building company was engaged after previous contractor Walter Lilly & Co withdrew after saying its staff had been subjected to threats and intimidation.