London Scientists say conclusive data show there is no question circumcision reduces men's chances of catching HIV by up to 60 percent - a finding experts are hailing as a major breakthrough in the fight against AIDS.
The question now is how to put that fact to work to combat AIDS across Africa.
The findings first were announced in December, when initial results from two major trials - in Kenya and Uganda - showed promising links between circumcision and HIV transmission.
The full data from the trials, carried out by the U.S. National Institutes of Health, were published today in The Lancet.
Circumcision long has been suspected of reducing men's susceptibility to HIV infection because the cells in the foreskin of the penis are especially vulnerable to the virus.
A modeling study last year projected that in the next decade, male circumcision could prevent 2 million AIDS infections and 300,000 deaths.