A third of people believe a woman is partially or completely responsible for being raped if she has behaved flirtatiously, a survey suggests.
Fewer than 6% of reported rapes result in a conviction
The Amnesty International poll of 1,000 people also found over 25% believe she is at least partly to blame if she has worn revealing clothing or been drunk.
Amnesty says the "shocking" findings show government policies are failing.
And the director of public prosecutions told the BBC the report "highlights some areas of real concern".
Ken Macdonald QC, who is in charge of prosecutions in England and Wales, spoke to BBC Radio 4's Woman's Hour.
"The idea that a third of our people think that if a woman flirts she has only herself to blame if she is raped is, I think, quite shocking," he said.
"These are jury trials. The jury is the community in the courtroom and it is reasonable to suppose the jury brings into the courtroom a lot of the attitudes we have been reading about."
The Home Office says it has changed the law to try to improve conviction rates.
"We have made a number of changes to the legal system and to how the police and Crown Prosecution Service work, to put victims needs first and to make it easier for cases to get to trial and secure convictions," a spokesman said.
"We are determined to close the gap between the increasing number of rape cases reported and the low number of convictions."
However, the Amnesty poll, carried out by ICM, found that most people in Britain had no idea how many women were raped every year in the UK or how few of the cases reported to police resulted in a conviction.
Almost all, 96%, said they either did not know the true extent of rape or thought it was far lower than the true figure. Just 4% thought the number of women raped exceeded 10,000.
The number of recorded rapes of women in 2004/5 was 12,867 - up 4% on the year before - although police estimate that just 15% of rapes come to their attention. Only 6% of reported rapes result in a conviction.
Amnesty International UK director Kate Allen said the poll, part of its Stop Violence Against Women campaign, had uncovered "disturbing attitudes".
She said: "It is shocking that so many people will lay the blame for being raped at the feet of women themselves and the government must launch a new drive to counteract this sexist 'blame culture'."
The research exposed the scale of public ignorance over rape as well as the "dreadfully low" conviction rates, she added.
"The government has an international duty to prevent this gross human rights violation yet it's clear that the government's policies on tackling rape are failing and failing badly."
Joanna Perry, policy manager at Victim Support, said it was alarming to read that so many people appeared to believe that a woman was responsible for inviting a rape or sexual assault.
"Rape is an appalling crime and has a devastating effect on victims and those close to them. In other words, nobody asks to be raped," she added.
And Ruth Hall, from the support group Women Against Rape, criticised "prejudices" in the court system.
"They still put the woman on trial, including her sexual history with other men, which is supposed to be banned and blame the woman for what happened to her and hold her accountable," she said.