A 2010 study led by the government-funded Medical Research Foundation says that in Gauteng province, home to South Africa's most populous city of Johannesburg, more than 37 percent of men said they had raped a woman. Nearly 7 percent of the 487 men surveyed said they had participated in a gang rape.
More than 51 percent of the 511 women interviewed said they'd experienced violence from men, and 78 percent of men said they'd committed violence against women.
A quarter of the women interviewed said they'd been raped, but the study says only one in 25 rapes are reported to police.
A survey by the same organization in 2008 found that 28 percent of men in Eastern Cape and KwaZulu-Natal provinces said they had raped a woman or girl. Of the men who had committed rape, one third did not feel guilty, said Rachel Jewkes, a lead researcher on both studies.
Two-thirds of the men surveyed in that study said they raped because of a sense of sexual entitlement. Other popular motivating factors included a desire to punish women who rejected or angered them, and raping out of boredom, Jewkes said.
"Rape is completely trivialized by a great number of men. It is seen as a legitimate activity," she said.
Jewkes believes South Africa's history of racial division and associated trauma is part of the reason of the high incidence of sexual violence in the country.
"Apartheid has contributed to culture of impunity surrounding rape in South Africa," said Jewkes. Men who were abused or experienced trauma during their childhood are much more likely to rape, she said, adding that apartheid destroyed family life, fostering violence and anti-social behavior.
The apartheid period also saw very little enforcement of common law, which has contributed to a culture of impunity, said Jewkes.
"We need to start interventions in childhood, focusing on building a more empowering childhood environment in South Africa, especially for boys," she said, "and we need to make it worth their while for women to report sexual violence."
The new study, conducted with a gender rights advocacy body, is the first community-based study of its kind with women in 12 years.
The group hopes to replicate the study across southern Africa.