German exports plunged by their largest amount since the height of the global financial crisis in early 2009.
German imports also fell sharply in the latest sign that Europe's largest economy lost momentum in the third quarter.
Data from the Federal Statistics Office showed seasonally-adjusted exports sliding by 5.2% to €97.7 billion month-on-month and imports tumbling by 3.1% to €78.2 billion.
This is the biggest one month drop since November 2012.
The country's trade surplus also narrowed to €19.6 billion.
The data follows sharp declines in industrial orders and output in August, suggesting that waning demand from abroad, particularly China and other emerging markets may be leaving its mark on Germany.
Economists polled by Reuters had been expecting much smaller declines in exports and imports of 1.2% and a surplus of €22.5 billion.