Last April the trial, involving a pill that would provide small protective doses of anti-retroviral drugs to uninfected people, was halted when it was found that women were still becoming infected.
But scientists at an AIDS conference in Seattle this week were told that blood samples from the infected women showed only a quarter of them had any of the drug in their bloodstream, The New York Times reported.
It is not known for sure why many women declined to take the drug,Truvada, but AIDS still carries an enormous stigma in Africa and the presence of an AIDS drug in a home might imply someone living there is sick, said Mitchell Warren, executive director of the prevention advocacy group AVAC.
Truvada had protected women in another study, he said.
The African trial was one of several experimental AIDS treatments presented at the Conference on Retroviruses and Opportunistic Infections.