Bucking the national housing market's slide in 1990, home prices in the Washington area still increased slightly last year, according to data released yesterday by the National Association of Realtors.

Based on the NAR's figures, the median single-family home here cost $150,200 in 1990, compared with a 1989 price of $144,400 and $132,500 in 1988.

However, the number of properties sold declined sharply last year, reflecting buyer uncertainty over economic conditions and an unwillingness by many sellers to lower prices in line with reduced demand, brokers and agents said.

The NAR did not break sales volume down by metropolitan areas, but Virginia and Maryland showed large statewide decreases -- 27.2 percent in Virginia and 24.6 percent in Maryland -- while the District slipped 6.5 percent.

Figures compiled by Rufus S. Lusk & Son Inc., a real estate information service based in Silver Spring, showed that sales in the metropolitan area declined 17 percent for the first 11 months of 1990 while the median price was essentially unchanged at $195,904.

The Lusk figures include newly built houses, while the NAR's figures were solely for resales.

The median price is the middle price -- half of the sales prices were higher and half lower. It tends to be lower than the average price because there are more transactions in the lower-price range, but it is considered a better gauge of the market.

Both price and sales figures showed that the Washington market remains much stronger than others that boomed in the 1980s and then turned soft. The median price in the Boston area, for example, dropped from $181,900 in 1989 to $174,200 last year, while the Bergen-Passaic area of New Jersey outside New York City slipped from $204,500 to $187,700. Even the popular Los Angeles area dropped from $214,800 to $212,800, the NAR figures showed.

And brokers and agents here said that there has been a perceptible pickup in the Washington market in recent weeks. So far, it has been mostly in "traffic" -- people coming to look -- but brokers said the interest appeared serious and they expect it to be reflected in sales data for late January and February.

"It's across the market in both price and geography," said P. Wesley Foster Jr., head of Long & Foster Real Estate Inc. Even the Hampton Roads area of Virginia, from which many residents have been sent to the Middle East, has felt the change, he said.

And Foster said a recent open house at an $800,000 home in Chevy Chase attracted 60 lookers. Long & Foster's Georgetown office, which had the listing, "was thrilled," he said.

Declines in asking prices, coupled with falling interest rates, are bringing first-time buyers back into the market as well, said Don Denton of Dale Denton Real Estate Inc.

Denton said a property on Capitol Hill, for example, that might have been priced at $250,000 two years ago might now be listed at $200,000. On top of the $50,000 savings, lower mortgage rates would save the buyer $43,000 over seven years.

"There's a terrific shift of wealth going on right now," he said, mostly "to the next generation of home buyers."

....FOURTH-QUARTER MEDIAN FOR EXISTING HOMES,.....

......COMPARED WITH 1989 FOURTH QUARTER...........

UP.........................Price....Percent Change

Baltimore...............$102,300...............4.8

Charleston, S.C..........$76,500...............4.9

Chicago.................$116,800...............6.9

Cleveland................$78,400...............5.7

Des Moines...............$61,200...............6.6

Houston..................$68,700...............9.7

Portland, Ore............$80,900..............11.0

Sacramento..............$134,900..............11.8

Washington, D.C.........$147,200...............1.1

DOWN.......................Price....Percent Change

Boston..................$165,600.............. 8.0

Dallas....................$85,00.............. 7.3

Hartford................$152,400.............. 7.2

Lexington, Ky............$70,900.............. 6.6

Los Angeles.............$210,300.............. 3.1

New York................$168,000.............. 6.3

San Francisco...........$247,800.............. 4.9

Shreveport...............$57,900.............. 9.5

BY REGION..................Price....Percent Change

Northeast...............$134,700.............. 6.5

Midwest..................$72,100...............0.4

South....................$83,200...............0.5

West....................$137,400.............. 2.5

UNITED STATES............$92,200.............. 0.5

SOURCE: National Association of Realtors