Access to anti-Aids drugs is spreading rapidly in many developing countries, but major obstacles remain, the World Health Organization says.
Just 2% of HIV positive Africans are getting drugs
The WHO target is for three million people to be getting anti-retroviral medicines (ARVs) by the end of 2005.
Some 700,000 people in poor countries were taking the drugs by December 2004 - a 50% rise in six months, the latest WHO report said.
It said good progress had been made in sub-Saharan Africa and parts of Asia.
But the situation was less satisfactory in eastern Europe, central Asia, North Africa and the Middle East.
"If we carry on doubling the number treated every six months, we are on course to meet our target of three million by December 2005," WHO HIV director Jim Kim told BBC News.
Worldwide, some 6m people urgently need the Aids drugs.
Some 41% of those who need ARVs and are unable to get them live in just three countries - India, Nigeria and South Africa.
The report also said there was a funding gap of $2bn.
The WHO said that those who are getting treatment are enjoying "dramatic" health benefits, with a 90% survival rate after one year of therapy and 80% after two.
Of those getting ARVs, some 275,000 are in Latin America, led by Brazil, which makes cheap generic drugs and where there is universal access for those who need them.
World: 700,000 in December 2004
Latin America: 275,000 - 65% coverage
Africa: 310,000 - 8% coverage
Africa: 150,000 in June 2004
Asia: 100,000 - 8% coverage
Asia: 50,000 in June 2004
Europe and ex-USSR: 11,000 - 10% coverage
In Africa, the worst affected continent, the picture is mixed.
The drugs are becoming more readily available in Cameroon, Kenya, Swaziland, Uganda, Zambia but giants Nigeria and South Africa are making dragging their heels.
The BBC's East Africa correspondent Ishbel Matheson says greater access to antiretroviral drugs has brought hope for sufferers, but also exposed the limitations of ramshackle health systems and overblown bureaucracies.
In Tanzania, she met one women left too weak to tend her field by Aids, who had never heard of the drugs.
Her carer said that knowing about the drugs would not help much in a country where just 1% of those who need ARVs can get them.
Neighbouring countries, such as Kenya and Uganda, are doing better but there is still a long way to go.
HIV activists say rural communities still have little access to the drugs.
Poor people often cannot afford the bus fare to travel to provincial hospitals.
Ignorance about antiretrovirals is also worrying: one campaigner said those with HIV often seem to know more about the drugs than the doctors and nurses administering them.
In Botswana and 10 Latin American countries, more than 50% of those in need are already getting ARVs and two badly affected countries - Uganda and Thailand - are due to join them early this year, the WHO said.