The price of a typical UK house fell by 0.2% in April, taking the average UK house price to £164,134, the Nationwide house price index found.
Robert Gardner, Nationwide's chief economist said the 0.2% drop in April is the fourth time in five months that prices have declined.
House prices are now 0.9% lower than April 2011.
"Much of the recent softness in measures of housing market activity and house prices is likely to relate to the expiry of the Stamp Duty holiday in late March. This provided a temporary boost to house prices in early 2012 as buyers brought forward purchases that would otherwise have taken place later in the year", said Gardner.
He added: "This effect should fade in the months ahead, and measures such as the government's NewBuy scheme should provide some support to buyer demand.
"However, the challenging economic backdrop suggests that a significant acceleration in prices or activity is unlikely in the near term."