Nigeria's government will provide all anti-retroviral drugs needed to fight HIV/Aids free of charge within two weeks, a health ministry official says.
Many Nigerians do not get the right doses due to lack of funds
Dr Abdulsalami Nasidi told the BBC the government planned to have 250,000 people on the drugs within a year.
After India and South Africa, Nigeria has the most HIV infections at 4m.
The BBC's Africa editor Martin Plaut says with such a high infection rate, fighting HIV has now become a national priority in the country.
Nigeria has been stung into action by criticism from the aid agency Medecins Sans Frontieres (MSF) that the government was asking Aids patients to pay for their drugs, which it got free.
The project will be financed by a $250m grant from the Global Fund to fight Aids, tuberculosis and malaria as well as from money released after Nigeria's international debts were cancelled.
Much of the rest of funding has been promised by the United States.
This has meant that charges for administering the drugs, which put them beyond the means of the poor, have now been scrapped.
"Those that are already receiving the treatment that were paying that token money will just be getting the drugs free of charge. [For new patients] all the drugs will also be given to them free of charge," Dr Nasidi told the BBC.
Medecins Sans Frontieres' research found nearly half of people on drug treatment in Nigeria did not receive sufficient doses due to lack of funds.
With HIV patients having to pay for their drugs, many had been forced to beg or borrow to raise the money they needed, the medical agency said.
But Dr Nasidi said he hoped that providing free treatment would reverse this trend.
"To survive if you are infected with HIV/Aids, you must take the tablet daily. So now that we are giving free we hope more people should come in for treatment.
"And there will be less stigma in society, people will not discriminate against people carrying the disease like before," he said.