Wal-Mart reported a 3.5% decline in same-store sales. Analysts surveyed by Thomson Financial had expected a 1.1% decrease.
Wal-Mart warned last month it expected same-store sales in April to be anywhere from unchanged to down 2%, but business was much weaker because of disappointing apparel and home goods sales at its Wal-Mart discount chain.
Same-store sales at the discount stores were down 4.6%, while at the Sam's Club warehouse club division, same-store sales rose 2.5%.
The last time Wal-Mart reported a drop in same-store sales was last November, when the retailer posted a 0.1% decrease.
Wal-Mart said the slowing economy was a big factor in its sluggish performance. It noted that recent surveys of discount store shoppers show that consumers are increasingly concerned about rising gas prices, which are now averaging over $3 a gallon nationwide.
Wal-Mart also blamed its performance on cold weather and the earlier Easter.
It also said product recalls by dog and cat food manufacturers contributed to a slowdown in pet supply sales during April.
The world's largest retailer said it expects May same-store sales to rise 1% to 2%.
Target suffered a 6.1% decline in same-store sales, in line with the 6.2% estimate. Target blamed the dropoff on a sales shortfall during the first two weeks of the month, and an earlier Easter holiday.
However, the company said it remains on track to meet its earnings goals for the year.
Costco Wholesale had a 7% same-store sales gain, better than the 6.3% estimate.
Federated, which operates Macy's and Bloomingdale's, posted a 2.2% decline in same-store sales, while analysts forecast a 1.7% gain.
JCPenney said its same-store sales fell 2.7%, more than the 0.8% analysts expected.
Among upscale retailers, Nordstrom recorded a 3.3% gain in same-store sales, which was below the 4.2% estimate. Saks had a robust 11.7% gain in same-store sales, above the 6.7% estimate.
Gap, whose problems led to the departure of its CEO in January, suffered a 16% drop in same-store sales, much worse than the 7.1% decline that analysts had expected.
Limited Brands had a 1% decline in same-store sales, worse than the 1% gain that analysts had expected.
Abercrombie & Fitch posted a 15% drop in same-store sales, much worse than the 4.7% decline Wall Street projected.
Apparel retailer Bebe Stores had a 9% drop, worse than the 6.6% analysts forecast. Wet Seal had a 9.6% decline, more than the 8.3% estimate.
Gadget retailer Sharper Image, which has been languishing for months, suffered an 11% drop in same-store sales. Still, the results were better than the 25% decrease analysts expected.