Bolivia says that it has been re-admitted to the UN's anti-narcotics convention after persuading member states to recognise the right of its indigenous people to chew raw coca leaf, which is used in the making of cocaine.
Evo Morales, the Bolivian president, had faced opposition from Washington in his campaign against the classification of coca as an illicit drug.
"The coca leaf has accompanied indigenous peoples for 6,000 years," said Dionisio Nunez, Bolivia's deputy minister of coca and integrated development, on Friday. "Coca leaf was never used to hurt people. It was used as medicine."
The leaf was declared an illegal narcotic in the 1961 UN Single Convention on Narcotic Drugs, along with cocaine, heroin, opium and morphine and a host of chemical drugs.
Bolivia withdrew from the convention a year ago and said it would not rejoin unless coca chewing was decriminalised.
The country's condition for rejoining the convention met resistance from 15 countries, including the United States and the rest of the G8 group of industrial nations, according to UN spokeswoman Arancha Hinojal.
But the objections received by the United Nations ahead of Thursday's midnight deadline fell far short. In order to block Bolivia's return to the convention a full third of its signatories - or 63 - needed to object.
Among nations objecting were Germany, Mexico, Russia, Sweden, Britain, Japan, The Netherlands and Portugal. Notably, neither Peru nor Colombia, the world's two other cocaine-producing nations, filed objections. Nor did any other South American nation.
Bolivia is the biggest cocaine producer after Peru and Colombia. But Morales, himself a former coca leaf farmer, says the plant offers health benefits.
Bolivians have chewed raw coca leaves for centuries as a mild stimulant that reduces hunger and altitude sickness.
To press for coca's decriminalisation, Bolivia's first indigenous president has chewed it at international forums, bestowed coca-leaf art on such figures as former US Secretary of State Condoleezza Rice and promoted the leaf as a "nutritional" ingredient fit for school lunches.
Morales' government said a celebration was planned for Monday with coca farmers.
"It's a great achievement but much remains to be done," said Rolando Vargas, a coca growers' leader in Cochabamba who belongs to Morales' union.