The decline was the biggest in a year. Still, sales are well ahead of last year's level for the same month, suggesting the housing market is improving slowly.
The National Association of Realtors said Wednesday that its index of sales agreements dropped to 95.5, down from March's reading of 101.1.
A reading of 100 is considered healthy. One year ago, the level was 83.5.
Contract signings typically indicate where the housing market is headed. There's a one- to two-month lag between a signed contract and a completed deal.
The decline could be a sign that a milder winter accelerated some home sales that normally take place in the spring.
Ian Shepherdson, chief U.S. economist at High Frequency Economics, said pending home sales rose in the first quarter of the year at a 28 percent annualized rate. Most economists were expecting a decline in April.
"The decline is bigger than we expected, but the underlying upward trend is still intact," Shepherdson said.
Contract signings rose 0.9 percent in the Northeast in April from March. But they fell in the other three regions. The biggest decline was in the West, where signings fell 12 percent. Signings dropped 6.8 percent in the South and 0.3 percent in the Midwest. Still, all four regions reported higher sales activity last month than in April 2011.
The March national reading was the highest since April 2010, the final month that Americans could qualify for a federal home-buying tax credit.
That helped drive completed sales of both previously occupied homes and new homes in April near two-year highs.
Home prices rose in March from February in most major U.S. cities for the first time in seven months, according to the Standard and Poor's/Case-Shiller index.
While the nation's weaker cities pushed the overall price index down to its lowest level since the housing bubble, price declines have slowed nationally and prices rose in 12 of 20 major markets.
Modest sales and rising prices add to other encouraging signs for the housing market, which has mostly slumped since the bubble burst five years ago.
Builders are breaking ground on more homes and requesting more permits to build single-family homes later this year.
Long-term mortgage rates have never been lower. The average rate on the 30-year fixed mortgage fell to 3.78 percent last week, the lowest since long-term rates began in the 1950s.
Still, the pace of home sales remains well below healthy levels. Economists say it could be years before the market is fully healed.
Many people are having difficulty qualifying for loans. Or they can't afford larger down payments required by banks. Some would-be buyers are holding off because they fear prices could keep falling.
A better job market has made more people at least open to buying. Employers have added 1 million jobs in the past five months, though the gains slowed in April and March. The unemployment has dropped a full percentage point since August, from 9.1 percent to 8.1 percent in April.
Economists estimate that employers will have added 160,000 jobs this month. The government will issue the May jobs report on Friday.
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