Australia’s trade deficit more than doubled to A$2.26bn (£1.2b; $1.96bn) in September, data showed.
Exports rose just 1% in the month, while imports were up 6% as Australia brought in more fuel.
The deficit, a balance of goods and services, widened a lot more than market expectations of A$1.95bn and compared to a revised deficit of A$1.013bn in July.
Falling prices of key commodities like iron ore is being blamed for the jump.
“The trade deficit for September came in worse than expected with falling commodity prices clearly weighing on export values,” said AMP Capital chief economist Shane Oliver.
Export earnings in Australia, home to some of the world’s biggest miners like BHP Billiton and Rio Tinto, have been impacted by the slump in prices.
The price of iron ore is down 40% this year, while thermal coal prices are hovering near five-year lows of A$63 a tonne on oversupply in the market and slower demand from China.