The Case-Shiller gauge is based on a three-month average, which means the April data was influenced by transactions in March and February.
"This month is better than last," David Blitzer, chairman of the index committee at S&P, said in a statement. "However, the seasonally adjusted numbers show that much of the improvement reflects the beginning of the spring-summer home buying season. It is much too early to tell if this is a turning point or simply due to some warmer weather."
Nineteen of the 20 cities in the index showed a year-over- year decline, led by an 11 percent drop in Minneapolis.
Washington showed the only increase, up 4 percent from April 2010.
New Lows
Six cities registered new post 2006-2007 lows, an improvement from the 12 areas in March. Prices in three regions, including Cleveland, Detroit and Las Vegas, dropped to the lowest level in 11 years.
Compared with the prior month, 13 of the 20 areas covered showed a increase on an unadjusted basis, led by Washington.
Reports earlier this month showed the housing market is yet to gain momentum. Sales of previously owned homes, which comprise about 94 percent of the housing market, were down 3.8 percent last month from April, the National Association of Realtors said.
Purchases of new houses dropped 2.1 percent in May, the first decline in three months, according to Commerce Department data. Competition from foreclosed homes is hurting demand for newly built dwellings.
The 1.8 million of inventory of distressed homes nationwide that may reach the market would take about three years to sell at the current pace, Daren Blomquist, communications manager at RealtyTrac Inc., said this month.