TRINITY College Dublin has purchased almost 10,000 mice and rats since the beginning of 2013 at a cost of almost €400,000.
The college use animals for biomedical research, as is practiced in several universities in Ireland.
UCD ran up a bill of over €200,000 for rodents for the same period.
Between January 2013 and November 2014 Trinity purchased 8,563 mice, 1,346 rats, 29 pigs and six rabbits for this scientific purpose.
The combined cost of buying in these animals cost the college €387,391.92, according to information released to the Herald under the Freedom of Information Act.
Animals are used in scientific research to investigate human medical conditions and remedies such schizophrenia and treatment for arthritis.
They are also used to study genetics.
"Scientists in TCD are required to demonstrate that there are no alternatives available before the ethical review process will permit the procedures," according to a spokesperson for TCD.
In 2013, 18,028 animals were humanely euthanised. Meanwhile by November 2014, 14,752 animals were also put down.
These figures include all of the pigs and rabbits bought in the same 23-month period.
The college also euthanised just short of 3,000 zebra-fish during this time despite having purchased no new fish.
UCD also purchased animals for scientific research under similar stringent ethical guidelines.
At the university medical research using animals is ongoing in several areas including lung disease, diabetes and cancer.
In this way, according to a college spokesperson, UCD scientists have made a significant finding relating to Multiple Sclerosis which could advance treatment in the future.
In 2013 and until December 2014 UCD had purchased 3,789 mice and rats at a cost of over €200,000. However, UCD declined to reveal how many of these rodents were subsequently put down during the same period.