Eleven nurses and midwives have become qualified to gather evidence in sexual assault cases, in an Australian first.

The Western Australian nurses graduated from a forensic training course in Bunbury, enabling them to take samples from sexual assault victims, which can be used as evidence in court.

Until recent changes to legislation, only doctors were authorised to conduct forensic procedures on victims and collect samples.

WA Police Minister Rob Johnson said the new arrangement would reduce the risk of lost evidence.

"Victims of sexual assault in regional areas were disadvantaged if a doctor was unavailable and often meant they had to travel excessive distances in order to undergo a forensic examination to collect vital evidence," he said.

"This situation led to significant shortfalls in the quality of forensic evidence due to the long delays in transportation, which is vital for any successful prosecution of offenders in court.

"Having trained nurses available on hand to carry out the internal forensic procedures will mean a better outcome for victims in country WA and will, in many instances, eliminate the potential loss of forensic evidence."

Mr Johnson said the program would be rolled out in regional and remote areas throughout the state.