Call it the gentrification of bankruptcy.

Once a dirty word whispered in corporate offices and courtroom corridors, bankruptcy has become a respectable tool of business. And, with companies controlling billions of dollars of assets seeking legal protection from creditors under bankruptcy law, it has become big business.

Six of the 10 largest bankruptcy filings in history have occurred in the last 18 months; those six companies alone had assets of more than $34 billion. In most of the cases, the companies filed for protection under Chapter 11 of the bankruptcy code, which means they intend to continue operating after reorganizing their finances.

Not that the stigma has been removed completely. Greyhound Lines, Drexel Burnham Lambert, Eastern Airlines and LTV Corp. all probably would have preferred not to file for what lawyers call Chapter 11. Nor is bankruptcy always pretty, as in Ames Department Stores Inc.'s announcement yesterday that it would close 221 stores and lay off nearly 18,000 employees as it tries to emerge from bankruptcy.

In fact, much of the public still equates bankruptcy with being broke, having failed. But the filings have become frequent enough among large companies that it may soon become to the 1990s what corporate mergers were to the booming 1980s, say business analysts and bankruptcy experts.

The number of corporate filings for bankruptcy protection from creditors actually has remained stable during the last two years and has gone down considerably from 1987, according to those who track such statistics. The dramatic change has been in the size of the companies making the filings.

"Huge, huge companies are going bankrupt," said Joseph Kelly, a bankruptcy attorney with Dow, Lohnes & Albertson in New York.

Does this mean the economic sky is falling? Not necessarily, say economists and bankruptcy experts. They say the number of big firms reorganizing corresponds to their rush in recent years to take on huge debt, leaving them vulnerable to the slightest economic downturn.

"During the {leveraged buyout} craze, it became fashionable to place levels of debt on companies that {were} previously inconceivable," said Murray Drabkin, head of the bankruptcy department in the Washington office of Cadwalader, Wickersham & Taft.

"A lot of the problem lies in the imprudent investment and lending policies of the last decade," said Roger M. Whelan, a former D.C. bankruptcy judge who is a partner at Washington's Shaw, Pittman, Potts & Trowbridge.

"Allied and Federated department stores were making money," said Kelly. "So it's not the economy. It was the debt they were lugging around." Allied and Federated were two of the department store subsidiaries of the now-bankrupt Campeau Corp. Their holdings included the Bloomingdale's and Abraham & Straus department store chains.

Even when unusual factors cause troubles in a particular corporation or industry, debt seems to be the back-breaking straw. Western Union Corp., which is attempting to avoid bankruptcy, lost much of its business to the facsimile machine. Greyhound had a strike. But analysts say that the greatest blow for each was its large debt burden.

Bankruptcy watchers say that the boom in big bankruptcies has just started and it may take three to five years to cycle through it. Many of the risky, high-yielding junk bonds that financed the corporate transactions of the last decade had interest rates that ratchet up for several years, causing debt burdens to intensify over time.

"This is just the beginning," said Drabkin. "It's survival of the fittest, and companies with heavy debt loads are not the fittest, they're the weakest."

In addition, the bursting of the real-estate bubble in many areas of the country will mean more Chapter 11 filings for real estate and related companies, others said.

The surge in big-company bankruptcies has left many service professionals scrambling to handle all the work. Lawyers who practice in the field are inundated with job offers and seldom see their families because of long hours these days, they say.

"All the law firms are really desperate for bankruptcy experts," said Kelly. "I get calls from headhunters every week. There just aren't enough to go around right now."

In addition, investment bankers, accountants and workout specialists -- those who advise clients who are trying to avoid bankruptcy or help those who have filed to reorganize -- find themselves busier than ever.

There's also a cottage industry of investment companies that trade distressed stocks and bonds of troubled institutions. And there are investment funds that buy them -- known in the trade as the vulture funds.

It is often said that the only people who make money in a bankruptcy situation are the lawyers. In fact, the lawyers themselves admit that a typical big-company workout can take from two to four years, generating tens of millions of dollars in legal and accounting fees along the way.

They add that those costs can often be less than the interest on highly leveraged debt, which a company can forgo paying while it reorganizes. The losers, of course, are the bondholders and other creditors who are not paid the sums they were owed before the bankruptcy filing.

Despite the relative financial advantages of bankruptcy for some companies, there are still many that try to avoid it. After all, bankruptcy filings can damage reputations, lead to enormous legal and accounting fees and minimize the flexibility that corporate executives have to make decisions. Well-known companies such as West Point Pepperell Inc., Interco Inc., Southland Corp., J.P. Stevens & Co. and Western Union are said to be among those renegotiating their debts to stay out of bankruptcy court.

But there's no doubt that for both the companies and the professionals involved, bankruptcy has taken on a new respectability.

"When I graduated from Harvard Law School in 1953, if someone had referred to me as a bankruptcy lawyer, I would have been offended," said Drabkin, who has worked on the bankruptcies of the A.H. Robins Co. Inc. and Equity Programs Investment Corp. "But today I would take no more notice of it than any other respectable practice of law."