Almost two weeks after the assassination of Egyptian president Anwar Sadat, the U.S. Embassy cannot say with certainty how many others were killed and wounded in the bloody attack.

Following the Oct. 6 assault, a political officer was assigned to what seemed a routine task of compiling the casualty list for transmission to Washington.

When he encountered difficulties, extra officers were added to track down the information. But repeated contacts with the Foreign Ministry, Defense Ministry, office of the president and the Interior Ministry have produced a count, of eight dead and 24 wounded, that embassy officials consider tentative at best. A count by resident journalists puts the toll at nine dead and 32 wounded.

The troubles of the inquiring embassy officials illustrate the more general problems that U.S. diplomats in Cairo encounter daily, trying to keep abreast of important and complex internal developments in this strategic nation where Washington has invested so much money and hope.

In this largest U.S. diplomatic mission in the world, performance has suffered from overdependence on official information from the Egyptian government, shortage of other sources able to provide a countering view and unfamiliarity with the intricacies of Egypt among a vast majority of the massive embassy staff who are, for the most part, recent arrivals. Only a tiny minority of the Americans speak Arabic, the country's predominant language.

"I haven't been here long enough to develop the sort of contacts I need to really do the job," said a key embassy department head who, like most of his senior colleagues, only arrived in Cairo this summer. "Obviously we have not got this place wired for sound. We have a lot to do."

That became obvious with the embassy's surprise that Sadat had been killed by a commando group led by a lieutenant from the Army -- which they had been assured was cleansed of any potential subversive Islamic extremists. It was underlined by the fact that the embassy took six hours to determine that Sadat had indeed been killed, and by the problems that have dogged efforts to compile the exact casualty list.

Discussion of such lapses has made the diplomats edgy about any comparison of their performance with that in the U.S. Embassy in Iran during the waning days of the rule of the late shah -- also made a pillar of Washington's policy in the region until his overthrow in 1979 by Moslem fundamentalists.

To compare Ambassador Alfred L. Atherton Jr.'s embassy in Cairo today with that of William Sullivan's in Tehran is, in the words of one U.S. diplomat here, a "flawed analogy" resulting from public obsession with the experience in Iran.

Certainly there are differences. In Iran, U.S. diplomats -- and the CIA -- were prohibited by an unwritten accord with the shah to contact members of the Iranian opposition; in Cairo under Sadat, embassy personnel maintained contacts with the official opposition.

In Iran, U.S. diplomats failed to perceive the ultimate force of the Islamic fundamentalist movement that toppled the shah until it was too late; in Cairo, embassy political officers regularly have monitored Islamic fundamentalist demonstrations and tried to assess the strengths and leadership of the burgeoning Islamic movement in Egypt.

The one area where comparison with Iran seems unavoidable, however, is the extent to which, given the autocratic nature of both the shah's and Sadat's governments, the U.S. ambassadors in Tehran and Cairo relied on the perceptions of the rulers.

Most important information in Cairo, as in Tehran under the shah, was passed directly to the U.S. ambassador by the ruler -- or here, by his deputy, then-vice president and now President Hosni Mubarak.

In Egypt's system, power and policy decisions were so strictly the monopoly of the ruler that even key ministers were kept in the dark about policies until they were ready to be sprung on the public.

Yet Sadat was impeded from knowing all the important currents. Those below often feared to tell him. At the same time he was distracted by his concentration on international affairs -- particularly negotiations with Israel under the Camp David accords.

If the U.S. officials continued to believe in Sadat's personal popularity in Egypt, this reflected in part Atherton's acceptance of Sadat's own confidence on that point. If the U.S. Embassy was also surprised by Sadat's assassination, it was in large part because Sadat had led Atherton and others to believe the fundamentalist extremists were neutralized by a crackdown in September. About 1,500 civilians and several hundred members of the military were rounded up, most of them accused of being Moslem extremists, as were Sadat's assassins.

Information-gathering at any level other than at the top presented U.S. diplomats with another problem. Mid-level Egyptian officials are often badly informed or reluctant to take any initiative.

"The people we deal with at a working level are often not very knowledgeable," said one diplomat. "When they are, they often only want to deal at an ambassadorial level, which, if you aren't the ambassador, makes things difficult."

Such problems have been compounded by turnover of key personnel. Some U.S. officials, who blame the problem on poor planning by the State Department's personnel office, said that 80 percent of senior diplomats in the embassy were transferred over the summer; only Atherton and his chief for the Agency for International Development had survived the rash of replacements.

In recent months the embassy has had a new deputy chief, head of the political section, economic chief, commercial counselor, International Communication Agency director, chief of the military cooperation mission and agricultural counselor.

The turnover in the economic section, diplomats said, has been 100 percent this year, as it was in the smaller commercial section.

Not only has there been a flood of new personnel in key jobs, but many of them also are not Middle East specialists. Officials insist that knowledge of the Arabic language is not that important for most jobs and that Arabists have been assigned where needed. But there are only 15 fluent Arabic speakers among the U.S. mission's 872 U.S. citizens. The embassy also has 500 local employes.

The problems caused by such a turnover of staff are compounded by the very size of it. Many useful members must devote their efforts to maintaining the bureaucracy.

In 1973, when ambassador Hermann Eilts arrived in Cairo to reopen the embassy after the rupture of relations in the 1967 Arab-Israeli war, he had a staff of six Americans. Three years later his staff had grown to 35, a mission that is remembered by journalists and Egyptian officials for its devoted professionalism.

Eilts tried during the rest of his five-year tour to resist Washington agencies' penchant for sending what he called "a lot of straphangers," but when he left the staff had grown to 190. In a departing interview, he said, "It could get out of hand. It's a mistake." Yet the growth accelerated.

After the 1978 Camp David accords, hundreds of Americans were rushed to Cairo to help administer the military and economic aid that flowed from Sadat's agreement to make peace with Israel. Today, two years after Atherton replaced Eilts, and with a combined military and economic aid program topping $1.5 billion a year, the embassy plans a 14-story building to contain the swollen staffs.

For all the size of the U.S. official establishment, only a handful is involved in keeping Atherton and the U.S. government abreast of critical events and trends in Egypt.

His key staff is drawn from 12 political officers, eight economic reporters, ICA's 10-member information staff, and 12 military attaches. Of the 125 members of the immediate chancellery staff, 44 are administrators and 18 are Marine guards.

AID has 438 Americans here, including 300 contract employes, and 255 in the office of military cooperation oversee U.S. military equipment deliveries and the training of Egyptians in its use.

Some diplomats complain privately that the growth of the mission has been so great and so fast that it has detracted from rather than increased the efficiency of the embassy.

"Somewhere there is a point of diminishing returns in the number of people staffing a mission," said one diplomat who wished to remain anonymous. "The embassy here was a great and professional institution when it was still small and manageable. Now it has grown beyond all imagination and in the process even the level of confidence has declined."

Certainly the administration of such an establishment as well as the demands of monitoring Egypt's negotiations with Israel have limited Atherton's ability to focus on the internal Egyptian issues -- on which U.S. Middle East policy ultimately may depend.

Yet Atherton, in an interview, said: "I am convinced we have had all the access to the Egyptian government and all elements of society necessary to remain well-informed. We have been aware of the need to understand the body politic of Egypt, what the trends are, and we have had the understanding of the government of Egypt in that effort."

Atherton said his embassy has not been caught off guard by events, despite the surprise of Sadat's assassination, which, he points out, could hardly have been predicted.

He says that the fundamentalist movement, which appears to be the only significant opposition to the Egyptian government, has not proved capable of staging a mass rising against the government such as Ayatollah Ruhollah Khomeini's in Iran. Thus he indicates that the embassy's conclusion, that the Moslem extremists had little grass-roots support in Egypt, was accurate.

In private, U.S. diplomats express confidence, still, that the Egyptian government -- if not the U.S. Embassy -- has the ability to discover subversives. These officials say no serious danger to the government is expected from that quarter, even if it can cause isolated incidents.