The Rwandan Survivors Fund (SURF) has been awarded £4.25m - its largest ever grant - by the Department for International Development.
The five-year grant will help more than 2,500 women survivors of the Rwandan genocide, who were raped and deliberately infected with HIV/Aids, to get anti-retroviral treatment (ART).
The money will be used to enhance the capacity of four existing local health clinics and their outreach services. At present only 99 women survivors have access to ART, 23 of them as a result of private funding by SURF.
SURF director Mary Kayitesi-Blewitt said: "The real challenge now is to engage more governments to add to DFID's funding, to enable SURF to help even more women survivors in Rwanda."
A DFID statement said: "We hope others will contribute to SURF's campaign to help the thousands more women survivors still needing access to treatment."
An estimated 25,000 women and girls were raped and infected with HIV in Rwanda in 1994.