Hawai'i's residential real estate remains among the priciest in the nation, though sales transactions are slowing, new data from the National Association of Realtors show.

Hawai'i house and condominium sales tumbled 18 percent in the April-to-June quarter as most housing markets softened nationwide. Hawai'i was one of 28 states and the District of Columbia that reported fewer transactions during the quarter compared with a year earlier, the Realtors group reported.

Home sales and transactions are slowing as buyers react to higher real estate prices and interest rates. Nationally, sales of existing homes and condominiums were down 7 percent in the second quarter compared with the record-setting pace in the same period in 2005, the association said.

Honolulu remains one of the most expensive markets for home-buyers nationally, with prices ranking in the top 10 for houses and condominiums.

The data show Honolulu's average home cost $640,000 in the second quarter, up 10.8 percent compared with the same three months in 2005. It ranked as the fifth-most expensive area of 151 tracked by the Realtors group.

Condominium prices averaged $305,000 in Honolulu, or the seventh-highest nationally and almost 19 percent higher than the similar 2005 period.