Labor's Melissa Parke is stepping off the front bench to concentrate on the health of a sick family member.
She is the first member of Opposition Leader Bill Shorten's shadow cabinet to step down.
Ms Parke said in a statement that an immediate family member was facing serious health issues and she needed to make them her priority.
"Every one of us working in federal politics needs to strike a balance between the often extensive time and travel demands of parliamentary work, and the important ups-and-downs of family life," she said.
"At this point I need to make my family and my electorate work the primary focus of my time and energy."
The Member for Fremantle has been the opposition's junior spokeswoman for health since October.
Before the federal election she held several parliamentary secretary positions and became the minister for international development in July.
She said it had been privilege to work with the shadow ministry and she hoped to be able to contribute to its work again when the time was right.
Mr Shorten was confident she would make a significant contribution in the future.
"I know this has been a very hard decision for Melissa but I completely understand and respect her need to spend time close to her family," he told AAP in a statement.
