Undated (AP) _ While many homeowners rushed to refinance mortgages with lower interest rates this winter, others were left out in the cold, casualties of the soft real estate market.

Once again, the big losers were those who bought when home prices peaked in the late 1980s. Not only are they unable to sell now without taking a substantial loss, but they've been denied a chance to become more financially comfortable where they are.

Most banks won't lend out any more than 80 percent to 90 percent of the current appraised value of a home, so when values decline, that makes less money available for refinancing.

''They're in a catch-22 right now: They can't sell because they won't make their money back and they may not be able to refinance ... because they may not qualify,'' said John Hickey, senior mortgage underwriter for First Trade Union Savings Bank of Boston, an area hard hit by slumping housing prices.

Hickey and his colleagues have seen growing evidence of this problem nationwide since the start of the year, as more homeowners sought to refinance their old loans to take advantage of a drop in fixed mortgage rates into single-digit territory. The national average for conventional 30-year fixed- rate mortgages fell below 9.5 percent last month, a 4-year low, although rates have risen slightly since then.

By refinancing, homeowners can cut their monthly house payments or rid themselves of fickle adjustable rate mortgages, which reflect prevailing market interest rates. In some cases, homeowners with low mortgages can even refinance beyond their balance and use the excess for other expenses, a procedure known as ''cashing out.''

Mortgage bankers across the country say there's been a tremendous increase in mortgage activity in recent weeks, with refinancings making up as much as 40 percent of their business. They usually account for around a quarter of mortgage activity, they say.

''Last week was probably our busiest week in two years,'' said John Battaglia, a vice president at Boston Five Cent Savings Bank.

But Battaglia suspects the rate of refinancings would be even higher had it not be for the tenuous real estate market.

''We're seeing a lot of people calling in and saying, 'I have a $200,000 house that I bought two years ago and I have a mortgage on it for $180,000. I think the house is only worth around $180,000 now. What should I do?''' said Battaglia. ''It's tough.''

The homeowners described in that scenario were told to stick with their current mortgages because they'd only be eligible to receive around $162,000 in a refinanced loan, or 90 percent of the current value of that home under standard bank guidelines. To refinance they'd have to come up with an additional $18,000 - the difference between what's approximatly left on the original mortgage and the new money that would be provided - as well as closing costs and other fees.

Sometimes financial institutions may bend the rules. ''Some lenders will refinance their own loans without a new appraisal,'' usually for their most credit-worthy customers, said Ross M. Strickland, executive vice president at Northeast Savings in Hartford, Conn.

But more than likely the banks would reject such an application.

Jeannette Parten, a vice president at the Pasadena, Calif.-based mortgage lender Countrywide, said less than 5 percent of all applications are rejected due to low housing appraisals because most people know ahead of time what their homes are worth.

Stickland agreed: ''I think people are savvy enough. They have a pretty good idea of their values before they apply.''