The university has students do procedures on live pigs as part of a trauma training course on its Newark campus.
But the Physicians Committee for Responsible Medicine says the use of the animals - which are put under anesthetized during the procedures and later killed - violates the Animal Welfare Act.
The group says in a letter to the U.S. Agriculture Department that the university should use anatomical simulators, as other New Jersey institutions that teach the class do.
UMDNJ officials say their teaching methods do not violate the law.
The USDA says the use of live animals isn't necessarily a violation.