"Encouraging results of the trial" with Japanese anti-viral drug Favipiravir will soon be published, the French medical research agency Inserm, which is in charge of the tests in Guinea, said on Thursday.
Eighty infected adults and children have received the drug.
Results "show a reduction in the number of deaths among adults and teenagers, with slower virus multiplication. Recovery is accelerated," said the French government in a statement.
The trial started on 17 December at a clinic in Gueckedou, eastern Guinea, in partnership with Guinean researchers and authorities, the French Red Cross and Doctors Without Borders.
The Ebola virus has infected 22,495 people, mostly in Guinea, Liberia and Sierra Leone, and has killed 8,981.