Like-for-like sales at Gap Inc dropped 16% in October, with international like-for-like sales, mostly in the UK, down 5%.
Like-for-like sales at the group's Gap chain fell 14%, while Banana Republic dropped 17%, with Old Navy showing the biggest fall of 20%.
Total net sales fell 12% to $1.08 billion (£680m). International like-for-like sales, mostly in the UK, were down 5%. This compares with a 6% drop the year before.
Gap Inc chief financial officer Sabrina Simmons said: "We continue to deliver merchandise margins significantly above last year despite the tough market conditions. We are reaffirming our full year earnings guidance and will continue to use inventory and cost management to offset what we anticipate will be a challenging holiday season."
For the thirteen weeks to November 1, group net sales were $3.56bn (£2.24bn), a drop of 8%. Sales for the period were down 12% on a like-for-like basis.