When Donald J. Trump, the flamboyant real estate tycoon, found his business empire in disarray, he could have called on any of Wall Street's top investment bankers to help him out of his troubles. Instead, he turned to an accountant in Los Angeles.

But the man he sought for counsel, Kenneth Leventhal, is no run-of-the mill, green-eye-shaded bean counter. At a time when the world of accountants and their firms is undergoing wrenching changes, besieged by government lawsuits and cutthroat competition for clients, the 70-year-old Leventhal is running ahead of the pack and, so far, ahead of his profession's problems.

Kenneth Leventhal & Co., the accounting firm Leventhal founded 41 years ago, ranks only 11th among CPA firms in revenue. But it is second to none when it comes to its expertise in real estate, according to government and industry executives. In the tumultuous real estate market of the last decade, everyone from Chase Manhattan Corp. to national developer Trammell Crow has come looking for it.

"As accountants, they are not in a class by themselves, though they are in the 'A' league," said Joseph E. Robert, chairman and chief executive of J.E. Robert Companies, a management firm that helps real estate companies resolve financial difficulties. "But as to real estate, they have no equal among national firms."

Its prowess and expertise have made Leventhal & Co. a beneficiary rather than a victim of the slump in real estate spreading throughout the country. Indeed, it has thrived on the misfortunes of real estate clients such as Trump who pay top dollar for the advice Leventhal doles out.

Since the accounting firm first got Trump's call for help six weeks ago, a team of experts in Leventhal's New York office has been working around the clock, meeting with Trump's lenders and trying to convince them that their client is worth more outside of bankruptcy court than in it.

Leventhal himself immediately flew to New York to help negotiate with Trump's four major banks -- Citicorp, Bankers Trust New York Corp., Chase Manhattan Corp. and Manufacturers Hanover Corp.

His presence, say real estate analysts, added credibility to Trump's side of the bargaining table in part because at least three of the four banks have themselves hired the firm to handle thorny real estate affairs of their own.

"If Trump said his properties were worth such and such, the bankers might not believe him. But if Ken Leventhal says they were worth it, nobody would challenge his word," said a New York real estate executive who asked to remain unidentified.

Leventhal, after helping to get the talks going, is now bicycling around Europe. His heir-apparent, Stan Ross, 55, and John Robbins, managing partner of the New York office, stayed behind to negotiate in Trump's marathon talks with lenders.

No matter what happens to Trump, Leventhal & Co. wins in the deal. The media coverage of Trump's troubles only adds to the cachet of the publicity-craving firm. And surely it will help the bottom line, for Leventhal & Co. gets paid whether or not its client succeeds in closing his deal.

Leventhal already has enjoyed fairly spectacular growth in the 1980s. Its revenue has more than quadrupled in the decade, rising from $33 million in 1981 to $141 million last year.

Its penchant for handing out advice rather than audits has also yielded Leventhal a rather unexpected benefit -- it never blessed the books of savings and loan institutions that have now fallen on hard times.

As a result, Leventhal was the natural choice of the U.S. government when it went hunting for firms to examine some of the controversial deals that thrift regulators made at the end of 1988, when dozens of investors bought ailing thrifts in exchange for an estimated $52 billion infederal subsidies. The Bush administration is expected to rely in part on the information that Leventhal supplies when the government decides which, if any, of the deals should be reopened or renegotiated to win better terms for taxpayers.

"When the government looked around for a firm that was not tainted ... they looked at Kenneth Leventhal," said A.N. Mosich, a professor at the University of Southern California School of Accounting.

Leventhal "clearly was the one they {the government} would turn to, because it did not have audit clients in this area, and it had the expertise in real estate, and the S&Ls are in trouble because of problems in real estate," said Mosich, an acquaintance of Leventhal's for nearly 40 years.

The professor also said it was natural for Trump, when he ran into trouble, to turn to Leventhal rather than to the investment banking firms of Bear Stearns or Merrill Lynch, two of Trump's key financial advisers in the past.

"Ken Leventhal and his staff know a lot more about the real estate market, about refinancing real estate, than any of the investment banking firms," Mosich said.

Leventhal, in a brief interview before he flew to Europe last week, was matter of fact about having Trump as a client.

"This is the bar of soap we sell," he said of the firm's financial advisory role. "This is what we do best."

Leventhal also has been able to maximize profits by using its recruiting and training policies to cultivate a loyal corps of real estate specialists. Their expertise translates into a higher billings rate than other firms enjoy -- $108 an hour for Leventhal, on average, compared with a $75 average rate for its competitors.

In revenue per partner -- a critical measure of success in accounting -- Leventhal leads all its rivals, including the so-called "Big Six" firms that dominate the industry. In 1989, Leventhal & Co. took in $2.1 million of revenue for each of its 67 partners. Arthur Andersen, the largest CPA firm when ranked by revenue, was a distant second, taking in $1.5 million for each of its 1,322 partners.

These numbers explain why partners at Leventhal & Co. are said to be the highest paid in the profession, earning annual salaries estimated to run over $1 million in many cases, compared with the six-figure salaries many rivals get.

But the pay doesn't come easy. Leventhal & Co. is known as the sweatshop of CPA firms, with a reputation for making its partners put in longer hours and do more hands-on work than rival firms.

Neither does Leventhal have an unblemished record. While the firm, unlike five of its Bix Six rivals, has not been sued by the federal government over the savings and loan debacle, Leventhal has not escaped the mountain of private-sector lawsuits that has piled up in the wake of the thrift fiasco.

Grant Thornton, a CPA firm that was the auditor of troubled Texas thrift Sunbelt Savings Association, was sued in 1988 by Sunbelt's new management. Grant Thornton turned around and sued Leventhal & Co., claiming it had relied on information supplied by the Los Angeles firm in connection with a major real estate deal that Sunbelt entered.

In addition, in 1981, Leventhal was censured by the Securities and Exchange Commission for deficiencies in auditing a Rockville-based restaurant chain, Emerson's Ltd.

Leventhal's style also has occasionally rankled its competitors.

Last year, it wrote a report that was presented to Congress criticizing the Big Six firm of Ernst & Young for its auditing of Lincoln Savings and Loan Association, the failed California thrift that has gained national attention because of the political influence of its former owner, Charles Keating.

"Seldom in our experience as accountants have we encountered a more egregious example of the misapplication of generally accepted accounting principles," Leventhal partner Roger A. Johnson told the House Banking Committee in November. The harsh language broke a decades-old taboo among auditors that no CPA ever publicly criticized another.

While many rivals praise the firm, some partners at Ernst & Young feel less than friendly toward it. Said one, "If Kenneth Leventhal fell off the face of the earth, I wouldn't be too upset, put it that way."