A cheap and easy-to-use pill could help combat malaria - which kills nearly 2m people a year in poor countries.
Malaria is spread by mosquitoes
The pill combines a classic malaria drug amodiaquine with a newer medicine containing artemisinin, which comes from a Chinese plant.
Developed by pharmaceutical company Sanofi-Aventis, patients need only take it twice a day - other regimes require as many as eight pills a day.
The malaria parasite has developed growing resistance to current drugs.
It is thought that part of the reason for this is that current treatments require patients to take a large number of pills, so many often do not complete the course properly.
Malaria kills between up to 2m people a year, and affects 500m
A child dies of malaria every 30 seconds in Africa
An estimated 40% of the world population, mostly living in the world poorest countries, is at risk
Malaria is the leading cause of death among the under-five children in sub-Saharan Africa
This leaves them vulnerable to recurrences of the disease, but also allows the parasite, which often it not totally killed off, to modify, and develop resistance.
Dr Allan Schapira, of the World Health Organization, said: "It seems to be a simple thing just to put two drugs together in one pill, but it really is an important step forward because it makes it much easier for people to take.
"It's very good news. It could have a major impact on the effectiveness of treatment."
Africa to benefit
Four main malaria drugs are used around the world, and often one drug will work in one country, but not in another.
The WHO recommends using those classic medications together with an artemisinin-based newer drug.
The new drug, developed in collaboration with the Drugs for Neglected Diseases Initiative (DNDi), is likely to be most effective in parts of Africa - where a child dies of malaria every 30 seconds - and Indonesia.
It is hoped the drug will cost less than $1 per three-day treatment for an adult, and 50 cents for a child.
There is already a combination tablet for malaria, using another of the four classic malaria drugs - lumefantrine.
However, that therapy still involves taking eight pills a day and is more than twice as expensive as the new combination pill.
Dr Bernard Pecoul, DNDi Foundation Executive Director, said: "One of the key goals of the DNDi's development strategy was to create a drug that is simple to use, at a cost below a dollar."
The World Health Organization estimates malaria affects up to 500m people world-wide each year.