More than 5000 Australian doctors have signed a letter asking Parliament to maintain the medevac laws.
The laws ease the transfer of sick refugees to Australia from offshore detention in Papau New Guinea and Nauru.
The Australian Senate is due to debate a government bill today that would repeal the laws which were pushed through by the opposition in February.
The Royal Australasian College of Physicians presented the letter, which says the medevac laws have the explicit support of the Australian Medical Association and all of Australia's medical societies.
The government's repeal bill has already passed the lower house but an independent senator from Tasmania, Jacquie Lambie, is expected to have the deciding vote.
College fellow Professor David Isaacs told SBS the laws needed to be preserved so that "doctors are the ones who decide who comes to Australia for urgent medical care, not politicians."
"Senator Lambie has talked about humanity and this is a chance for the Parliament to show that humanity," he said.
"Doctors are saying please keep the medevac bill as it is. The medevac bill is working. It is saving lives. It is getting desperately ill people to Australia."