South African Aids experts have called for a mass circumcision programme after studies showed it reduced the rate of HIV infection by up to 60%.
Some fear that circumcision could lead to more risky behaviour
Professor Alan Whiteside said all boys born in public hospitals should be offered the operation.
"It is so blindingly obvious that there are real reasons for circumcision," he said at a national Aids conference.
Some 5.5m South Africans have HIV - second only to India - and one person in nine is infected.
Some, but not all, of South Africa's ethnic groups practise circumcision.
"In South Africa, high proportions of men and women find it acceptable to be circumcised," said Neil Martinson of the Perinatal HIV/Aids Research Unit.
Health minister 'snub'
Some critics have, however, warned against mass circumcision, pointing out that it did not help women and could encourage men to feel they were immune and take part in risky behaviour.
But Mr Martinson said these fears were not borne out by studies.
Manto Tshabalala-Msimang is known as 'Dr Beetroot'
"People weren't going around and sleeping around more because they didn't have a foreskin," he said.
Last year, studies into the link between male circumcision and HIV infection in Africa were stopped because the evidence was so striking.
Meanwhile, organisers of the conference have denied reports that they snubbed controversial Health Minister Manto Tshabalala-Msimang.
"The committee confirmed that Dr Tshabalala-Msimang had been invited repeatedly to take part officially at the opening of the conference on Tuesday evening," said a statement from organisers Dira Sengwe.
Deputy President Phumzile Mlambo-Ngcuka had told the conference that Dr Tshabalala-Msimang had missed a session on Wednesday because she was unhappy with her allocated slot.
Dr Tshabalala-Msimang has often told people with HIV to eat garlic, lemons and beetroot, while casting doubt on anti-retroviral drugs.
Anti-Aids activists have long demanded her dismissal.
She has just returned to official duties this week after having a liver transplant.