GENEVA - The Swiss voted yesterday to join the rest of the world as members of the United Nations after sitting on the global sidelines for more than five decades.

Tallies reported from all precincts showed a nationwide margin of 55-45 percent in favor. The crucial second obstacle, approval by at least half the country's cantons, or states, was cleared by a much narrower 12-11 vote.

Impassioned appeals from nationalists fueled opposition to the government-backed referendum to join 189 countries in the world body.

Switzerland has long been a dues-paying member of some U.N. specialized agencies like the World Health Organization and the International Labor Organization.

But it remains, with the Vatican, an observer state in the U.N. General Assembly.

Seventy-five percent of Swiss rejected U.N. membership in a similar referendum in 1986, backing opponents who said membership would let East-West polarization compromise Swiss neutrality.

But the government, backed by Swiss industry, banks and interest groups, contended that the political climate has changed since the height of the Cold War, and that it is time for the 7 million Swiss to play a full role in the world. The government also feared another rejection of full membership would make Switzerland an international outcast with a selfish and uncaring reputation.

The country evidently agreed. Nationwide 1,484,818 people voted in favor, compared with 1,236,067 against. The division between cantons held at 11-11 for two hours until Zurich, the largest canton, weighed in on the side of the U.N. supporters, assuring their victory.

Opponents claimed U.N. membership would force Switzerland to abandon its cherished sovereignty and submit to the political dictates of the five permanent members of the Security Council, such as the imposition of sanctions on countries like Iraq.

The nationalists plastered the country with posters claiming that U.N. membership would mean wasting millions of dollars a year for nothing. Switzerland already provides logistical help to peacekeeping operations and invariably follows U.N. sanctions.

Leading the opposition has been Christoph Blocher, a billionaire industrialist who says Switzerland is successful and wealthy precisely because it is different.

"We have our system of direct democracy, neutrality and federalism. We would lose that if we became a member of the United Nations," Blocher said in a recent debate.

Blocher, a leader of the nationalist Swiss People's Party, swung a 1992 vote against Swiss membership in a loose European free trade pact, forcing the government to put aside plans to join the European Union.