World Trade Organization (WTO) members have agreed to uphold a rule that allows poor countries to import cheaper copies of patented medicines.
The agreement will extend a 2003 temporary rule
Its general council has agreed to make permanent a 2003 waiver that allows poorer nations to import generic drugs to treat serious diseases such as Aids.
The measure would become permanent by 1 December 2007, the WTO said. The current waiver remains until then.
WTO boss Pascal Lamy said the agreement showed the body's humanitarian concern.
US Trade Representative Rob Portman added that America was fully behind the move.
"This is a landmark achievement that we hope will help developing countries devastated by HIV/Aids and other public health crises," he said.
The European Union (EU) has also backed the change.
"The EU has worked hard for this outcome and welcomes that others have moved to make this possible," said EU Trade Commissioner Peter Mandelson.
And for the UK, Trade Secretary Alan Johnson said "this announcement should be an important step in making drugs available in poor countries.
"The lack of access to essential medicines in developing countries is one of the biggest health issues - and one of the gravest injustices - in the world."
Under the rule, poorer nations will be allowed to import the generic drugs for humanitarian reasons and not for commercial purposes.
Some of the larger developing countries, like India, hope that they will be able to sell antiretroviral Aids drugs to Africa under the deal.