Protests will be held outside Cardiff University today, against the institution's record when it comes to experimenting on animals.
The most recent figures obtained under a Freedom of Information request show that, in 2011, 51,826 animals were used for testing - 43,912 were mice.
Campaign group Animal Aid, one of the organisers of the demonstration, has described recent cancer research involving genetically altering mice as "agonisingly cruel and medically useless."
A petition against animal experimentation written by the other organisers, Cardiff Animal Network and Cardiff Animal Rights, gathered 2,000 signatures around in Cardiff in a day.
More top news
RAF veteran Andy Davies says the Royal British Legion helped him get back on his feet after problems with alcohol.
Lucy has the latest weather forecast for Wales
Plaid Cymru leader Leanne Wood has said her MPs won't back English votes for English laws until Wales gets an extra £1.2 billion a year.