SOFIA, BULGARIA, JUNE 11 -- Sunday's Bulgarian national election, in which reform Communists won a sweeping victory except in this capital city, was a jolting reminder that sharp differences in cultural and political outlook persist among the nations of Eastern Europe.

Bulgarian voters, about 84 percent of whom went to the polls, proved a resounding exception to their neighbors in the region who have tossed Communist governments out of power in recent months. In democratic elections in East Germany, Hungary, Yugoslavia, Poland and Czechoslovakia, reform Communists did not even come close to winning a significant role in new governments. In Romania, the Communist reform group that toppled dictator Nicolae Ceausescu easily defeated a poorly organized opposition, but in voting that was colored by overt and widespread intimidation.

But here, in a Balkan country that has not had anything resembling a free election in 58 years, the opposition was given wide access to national media for months before the voting. By the end of the campaign, the Union of Democratic Forces opposition alliance had managed to present Bulgarians with a cogent, Western-style, aggressively market-oriented alternative to the socialist state. And the voting process itself was relatively free of irregularities and intimidation, according to international observers.

The outcome suggests that most Bulgarians do not find communism to be an alien philosophy or a disguise for Soviet domination, as was the case in most of Eastern Europe. One important reason for this is that the Russian people are regarded here with something other than the special hostility long reserved for them in the rest of Eastern Europe. Bulgaria was for decades the most docile and cooperative of the Soviet Union's East Bloc satellites; in return, the country received relatively generous subsidies of fuel and raw materials and a ready market for industrial goods.

"We are Russophiles," said a senior adviser to President Petar Mladenov, who last November led the palace coup that toppled the 35-year dictatorship of Todor Zhivkov, a coup, the adviser said, that took place with passive support from the Soviet leadership. Bulgarian affection for things Russian is linked to one key historical event -- in the late 19th century, the Russian army provided crucial assistance in ridding this country of 500 years of hated Turkish rule.

Before Zhivkov's fall, the Communist regime here was repressive and frequently brutal, operating a network of concentration and labor camps that terrorized the country from 1945 to 1962. But the party also raised the postwar standard of living of most Bulgarians, providing them with a good system of roads, schools and health care. During the election campaign, the ruling party repeatedly warned that the opposition would upset the status quo, cut government subsidies and force everyone to scramble to survive. One senior party official predicted late last week that "the Bulgarian people will prefer security to the chance that a few might get rich."

Vote projections showed the Socialists -- as the Communists who have ruled here for 45 years have renamed themselves -- winning majorities in nearly every section of the country, cities and countryside alike. Only here in Sofia, a city of 1 million in which intellectuals, professionals and students form the opposition's core of support, did the Union of Democratic Forces win more than 50 percent of the vote.

The opposition alliance conceded today that the Socialists had won a majority of seats in the 400-member National Assembly, but that did not prevent tens of thousands of opposition supporters from taking to the streets of Sofia to protest the outcome. Crowds rallied in the city center shouting "Down with the Red mafia!" and other anti-government slogans as hundreds of cars flying UDF flags crisscrossed the city with horns honking.

Socialist leaders repeatedly have said they want to form a coalition government with the opposition, but key Democratic Forces leaders reiterated today that they would not take part in any such arrangement.

While the voting atmosphere on Sunday seemed surprisingly benign, there were pointed suggestions today that fear -- namely, fear of threats against rural people by local Socialist functionaries -- played a role in the vote. A statement by a delegation of 60 international observers concluded that, while the election itself was valid, fear and intimidation played a role, and there were widespread reports that local party officials had threatened elderly people, Gypsies and others with loss of pensions, apartments or jobs if they did not vote Socialist.

"A long history of dictatorship can affect the behavior of a voting population. When this is the case only the most aggressive reassurances by a government can overcome the fear people feel," the statement said. The U.S. government, which funds the two American foundations that organized the election monitoring teams, had urged Bulgarian leaders to reassure voters that their ballots were secret, but the observers concluded that the government's effort was "insufficient to overcome 45 years of harsh Communist rule and the lack of a political culture disposed to free choice in the rural areas."

Although fear of authority may have played a role in the Socialist victory, the four-month campaign appears to have politicized large numbers of Bulgarians in a way that would have seemed impossible nine months ago. Several observers described the rapid emergence of political freedoms here as a "remarkable achievement." After the November coup, the reform Communist leadership announced that it planned to move toward free multi-party elections as well as economic reform. While insisting that Bulgaria should stick with Marxist principles even as it ditched dictatorship, the new leaders tolerated an unprecedented level of free speech and assembly.

The coup and subsequent liberalization were greeted by many Bulgarians with jubilation and shock. Having no experience with democratic rule, they didn't quite know what to do with freedoms handed them by an unfamiliar breed of Communist reformers who seemed willing to tolerate criticism.

In the first few months after the revolution, the reform Communists stayed a step ahead of the opposition. The party renamed itself, renounced one-party rule, pulled its watch-dog cells from workplaces, proclaimed itself open to Western investment and even asked the opposition to join in an interim coalition government.

It was not been until the last few months that the Union of Democratic Forces, made up of 16 groups of former dissidents, managed to present a coherent message to voters.