Two new studies yesterday showed that the median home price in the Washington area is again creeping upward after several months in which prices were stable or declining.

A national study conducted by the National Association of Realtors, a real estate trade organization, found that the median price of existing homes sold in the Washington area rose 7.4 percent, climbing from $140,500 to $150,900 in the second quarter of 1990, compared with the same period last year.

An NAR spokesman said the recent increase helped Washington-area homeowners recover some lost ground.

"We're about where we were in the third quarter of 1989, when you look at the figures," said John A. Tuccillo, NAR's chief economist, who lives here. In the past year, the median price reported by the NAR on a quarterly basis climbed from $140,500 in the second quarter of 1989 to $148,300 in the third quarter, and then dropped in the last three months of the year to $145,600. The median price -- the midpoint at which half the homes in the market cost more and half cost less -- fell again in the first quarter of 1990 to $144,700.

Meanwhile, a regional review of real estate transactions compiled by the Silver Spring-based real estate information company Rufus S. Lusk & Son Inc. found the median price of both existing and new single-family homes sold here in May 1990 rose by a narrow 1 percent, compared with the previous May, to $196,005. The median price of condominiums, Lusk said, rose by 5 percent, to $107,843, in the same May-to-May comparison.

Last month, Lusk reported that the median price of single-family homes in April 1990 had fallen 5 percent from its April 1989 level. Rufus S. Lusk III, president of the company, said the increase in May reflected the "seasonal boost of the spring market," but added that, in general, prices here continue on a sluggish course.

Lusk said the flattening of prices will cause some short-term pain but produce long-term benefits. Local governments, he said, will likely suffer some budgetary shortfalls as construction declines.

On the other hand, Lusk said, the moderation in prices will mean more renters can become homeowners; it will assist employers who have had trouble attracting workers to the area; and it will give a much-needed respite to elderly people pinched by soaring property taxes.

Spokesmen for the NAR and Lusk attributed the discrepancies in the numbers they reported to differences in their reporting methods. The NAR conducted a quarterly study that included only the sales of existing homes. Its primary source of information was the multiple listing service, which means that the sales of new homes and properties sold by their owners are generally omitted. Lusk, on the other hand, included both new and existing homes, as well as houses sold by their owners because it compiles its figures from recorded sale documents. In addition, Lusk reported a monthly, rather than quarterly, figure.

In general, both locally and nationally, the more affordable the housing market, the better it is performing. Thus, the median rose in Prince George's County from $116,740 in May 1989 to $132,143 last May, while in higher-priced Arlington County, the median dropped from $244,129 to $225,683, according to Lusk.

Nationally, price appreciation has cooled in many areas that were previously super-heated, such as the coastal areas of California and New York City, the Realtors survey showed. In California, for example, prices declined by 0.5 percent in Los Angeles, dropping from $218,000 to $216,900. The free-fall continues in the New York City area, where prices fell 8.8 percent in affluent Bergen/Passaic areas, dropping from $212,300 to $193,600.

Elsewhere in the country, in areas where prices have been lower, appreciation is occurring at a rapid pace. Seattle/Tacoma had the nation's highest appreciation rate, with the median price climbing 35.3 percent in the second quarter to $147,600. About the only market that remains locked in a continuing hyper-charged pace is Honolulu, where the median price hit $345,000 in the second quarter, up 33.2 percent from the year-earlier period. .