A Toowoomba woman has been granted legal permission to remove her late fiance's testes in the hope of having a child.

The day after the man died unexpectedly in mid-April the woman lodged an urgent application in the Supreme Court to have his testes removed so she could one day use the sperm.

The court was given several sworn affadavits from the couple's friends, who said they had "made no secret" of their wish for a child.

The pair met in September 2015 and were engaged a month later.

They planned to get married this year and had already begun trying to conceive.

In making his decision, Justice Martin Burns said the testes had to be removed within 24 hours of death if the sperm were to ever be used.

"Those orders will... permit mature reflection ... whether to proceed with the use of any extracted material," he said.

"If an application for use for the purposes of fertilisation is made, the orders proposed today will ensure that such an application will not be rendered futile."

Lawyers representing the deceased man and his parents did not oppose the application.

The court ruled the man's testes were to be kept at an IVF facility of the woman's choice.

She must make a second application to the court before she's allowed to use the sperm.