The High Court in Cape Town ruled against German physician Matthias
Rath and US doctor David Rasnick, a former adviser to President Thabo
The case was brought by the pressure group the Treatment Action Campaign and the South African Medical Association.
They accused Dr Rath of conducting illegal trials among poor communities.
"It is declared that the clinical trials conducted in South Africa are unlawful," Judge Dumisani Zondi said in his ruling.
Matthias Rath and his Rath Foundation promote vitamin pills and
minerals which they say can reverse the development of HIV/Aids.
But critics say such trials had led to unnecessary deaths when HIV-positive people stopped using anti-retroviral drugs.
TAC and SAMA accused the South African government of not doing enough
to stop the trials and failing in its duty of care to the public.
Health Minister Manto Tshabalala-Msimang, who has
controversially advocated garlic and beetroot instead of
anti-retroviral drugs, denied the allegations.
Nathan Geffen of the Treatment Action Campaign hailed
the judgment as a victory for scientific governance, which he said had
been contested by the health minister and president.
South Africa has one of the world's highest incidences
of HIV. One in five adults are reported to be infected and an estimated
500,000 people are infected each year.