In a story from Tehran last week, The Washington Post reported persistent rumors that the shah's sister, Princess Ashraf, had been involved in drug smuggling. The Post has no substantive evidence that these reports are true, and regrets their inclusion.

As Shah Mohammad Reza Pahlavi, his wife and entourage of aides and bodyguards left Iran today for an uncertain future, at least one thing was certain: Wherever they go, the shah and his family will not be strapped for cash.

During the 53 years of the Pahlavi dynasty, the imperial family has amassed a great fortune estimated to run into billions of dollars. One Iranian economist estimates the assets of the entire royal family at more than $20 billion, a staggering sum that would probably exceed or at least equal the wealth of any of the other royal famillies of Middle East Oil-producing states.

The source termed the figure of $1 billion for the shah's personal fortune a "gross underestimate" and said it amounted to many times that.

The list of wealthy royal relatives who have left Iran includes virtually all the 63 princes and princesses who make up the imperial family. It is unknown precisely where they all are now. Various reports place them in retreats from the Seychelles Islands to Brazil.

According to palace sources here, the shah might end up in southern California. Last month, his ailing mother, Taj-Ol-Molouk, flew to Low Angeles to join her daughter, Princess Shams.

Three children of the shah left yesterday for the United States, along with his mother-in-law, Farideh Diba. The shah's other child, Crown Prince Reza, is taking advanced flight training in Texas.

The main instrument of imperial wealth both at home and abroad has been the Pahlavi Foundation, ostensibly a charity but in practice mainly a profitable investment house that represents much of the Pahlavi family's business interests and channels funds to its members.

The official record of the foundation's assets has never been published, but a list purportedly compiled by a dissident senior employee of the foundation and nnow circulating in Tehran names 207 firms in which the foundation or various royal family members hold shares. The interests range from major banks to a bowling club.

According to economic analysts and published accounts, a main source of Pahlavi wealth -- but one that has never been proven -- is Iran's oil income.

Discrepancies have been cited between oil revenue from direct exports declared by the National Iranian Oil Co. and foreign exchange earnings reported by the central bank.

One Western economist said that when he tried to forecast oil income, he found the discrepancy "was usually around $2 billion a year."

The central bank's explanation has been that the NIOC is not required to immediately convert foreign exchange and often keeps funds in foreign banks for a period.

But another explanation has been that part of the national oil revenue is diverted to a Swiss bank account of the Pahlavi Foundation for use by the royal family and the shah and to finance covert foreign operations by the Iranian secret police, SAVAK.

There has never been conclusive proof of this because the full account of the NIOC and the assets of the Pahlavi Foundation are considered state secrets.

But a document published in a Paris newspaper two years ago purported to show a $12 billion transfer from the NIOC to a Swiss bank account of the Pahlavi Foundation.

The foundation's annual report is limited to details of its educational, health and charitable services, including student scholarships and orphanages.

Never mentioned are the foundation's numerous holdings, which include banks, hotels, casionos, industrial and mining venntures, agriculture, construction firms and trading companies.

For instance the Pahlavi Foundation owns 10 percent of a joint venture in Iran with General Motors to assemble Cadillacs and other cars. It also entirely owns the Bank Omran, the fifth largest commercial bank in the country. In turn, the Bank Omran owns 5 percent of the First National Wisconsin Corp. Bank of Milwaukee and an estimated 50 percent of the Canal Street development project in New Orleans.

Aside from such known investments, the foreign interests of the Pahlavi Foundation remain a tightly held secret. But the recently compiled list of domestic holdings provides a revealing glimpse into the imperial family's business in Iran.

In addition to foundation interests, it details the innvestments of a number of Pahlavi family members. Not surprisingly, however, it makes no mention of what might be the most exotic family business.

According to a number of Iranian sources, Princess Ashraf, the shah's twin sister, and several former government officials have been deeply involved in the drug business. The sources say an assassination attempt in which Ashraf's car was raked with gunfire in southern France a year ago involved a rival gang of drug smugglers.

"Iranian opium and hashish was leaving the country, and heroin and cocaine was coming in," one source, with knowledge of Iranian business and the royal family, said of Ashraf's alleged drug smuggling operation.

The source said he knew of several cases in which people arrested on drug smuggling charges mentioned members of the Pahlavi family as their backers during police interrogation, but this was never brought up later in court.

"Ashraf was into anything that smelled of money," the source said.

He said many in the royal family fell out of favor with the shah temporarily at one time or another for various offenses, notably fighting among themselves.

"They're just like a pack of wolves," he said. "Sometimes they turn against each other."

According to the recent listing of family investments, the wife of Prince Ahmad Reza, the shah's half brother, holds shares in a prosperous insurance company. The shah's daughter, Princess Shahnaz, holds the Iranian shares of a Japanese joint venture to assemble bicycles and motorcycles.

Another half brother, Prince Mahmoud Reza, is a key shareholder in a tire manufacturing company. Princess Ashraf's vast business interests include sole ownership of an agribusiness company. Her son, Prince Shahram, is a shareholder in numerous firms, including the Shell Chemicals Iran Co. Another brother, Prince Gholam Reza, owns several firms, notably in construction and land development.

There would be nothing unusual in all this if not for what manny Iranian businessmen and palace watchers charge are the corrupt business practices of the royal family.

Among these are alleged abuses of the shah's power for financial gain, intimidation of competitors and extortion from other businessmen.

In many cases, a prominent Iranian businessman said, agents of royal family members would simply go through the official gazette of new companies and demand from a percentage of their profits.

A meat importer said that at one time an importer had to bribe one of three organizations to get permission to bring meat into the country. One was controlled by the shah's personal physician, the second by the wife of a prince, and the third by a former agriculture minister, now in prison.

More aggressive tactics are attributed to Prince Gholam Reza, Princess Asharf and Prince Shahram. The later is said to own islands in the Seychelles and sit on the board of some 240 Iranian companies.

One businessman charged that agents for Gholam Reza forced land owners south of Tehran to sell their property to the prince cheaply under threat of nationalization. Then, the source said, Gholam Reza built housing on the property and sold it for exorbitant prices.

Other sources say much of the blame lies with unscrupulous Iranian businessmen who offer shares and board memberships to imperial family members to get the political clout that greases the wheels of Iran's overwhelming bureaucracy.

Some say business agents of the family wrangle corrupt deals without the express knowledge of their employers.

A countercharge is that if some family members did not know about the corruption attached to their names, with their position secure and the money rolling in, neither did they really care.