Like-for-like sales were down 4% for the 20 weeks to January 18. They have been consistently negative for this period since 2005 but the retailer's strategy of focusing instead on margins is admired by City analysts.
Its 615 high street stores saw a fall of 6% but WH Smith said there was good margin improvement and costs were tightly managed.
In the retailer's travel division, which has 673 units at airports, railway stations and motorway services, like-for-like sales were down 1%, again with margin improvement, and a store opening programme progressing well.
The group said it had identified further opportunities for growth in both the UK and abroad.
It also began to deliver on its pledge of returning £50 million of cash to investors, buying 1.6 million shares at an average price of £9.57 - after last year reporting annual profits up 6% to £108 million.
Chief executive Stephen Clarke said: "During the period we have delivered another good profit performance across the group with costs tightly controlled and further improvement in gross margin.
"Looking ahead, we continue to plan cautiously and manage the business tightly while investing in new opportunities for future growth. We are confident in making further progress in the year."
WH Smith slashed £18 million of costs from its high street network during 2012/13 and has said it is targeting a further £22 million savings over the following three years.
The chain has weathered the downturn with the help of "impulse" offers such as a free bottle of water with the Telegraph newspaper, while shifting its focus away from lower-margin CDs and DVDs towards books and stationery.
Shares opened more than 2% higher today, with analysts at Cantor Fitzgerald Stockbrokers sticking by their forecast for profits of £108 million in the current financial year.