Statistics Canada says the country posted a merchandise trade deficit of $1.1 billion in August as lower oil prices weighed on exports.
The agency says the result compared with a revised deficit of $287 million in July. The initial reading for July released last month pointed to a surplus of $684 million for the month.
The result came as total exports fell 1% in to $64.3 billion in August.
Exports of energy products fell 3%, as shipments of crude oil fell 4.1%, mainly due to lower prices.
Total imports edged up 0.3% in August to $65.4 billion as imports of motor vehicles and parts rose 2.4%.
In volume terms, total exports edged up 0.1% in August, while imports increased 0.4%.