Cosatu's leaders recently had themselves tested for HIV-Aids after they were challenged to do so by the National Union of Mineworkers.
The miners' union (Num) leadership established a milestone in its HIV-Aids campaign when its entire membership in Carletonville was tested in June.
About 50 Cosatu leaders were tested last Tuesday.
Num spokesman Lesiba Seshoka said: "About 32 leaders tested and we then challenged Cosatu to do the same. Num is the biggest Cosatu union and we believe that leaders must lead from the front."
The Carletonville branch is one of the biggest, with 13000 miners.
Seshoka said mine workers were vulnerable because most worked away from home.
"We educate them about HIV-Aids," Seshoka said. "We tell them to have themselves tested and that HIV is a disease, not witchcraft. We also teach them to abstain, be faithful and to condomise."
Num's Aids desk is making headway. Most miners now regard HIV like any other illness. Seshoka said the Aids stigma was slowly disappearing.
He said there were no clear figures about how many mine workers had died from HIVrelated illnesses.
"Our figures are clouded by a variety of issues. Some doctors do not record Aids deaths. It is difficult to quantify deaths as miners are also plagued by diseases peculiar to the industry."