The survey was released for International Women's Day
Women in Iraq still lack security and basic services, despite an overall drop in violence six years after the US-led invasion, aid agency Oxfam says.
Reporting on a survey of about 1,700 women in five provinces taken last year, Oxfam described their plight as a "silent emergency".
It suggested more than half the women had suffered from violence.
A quarter did not have daily access to water supplies, and more than three-quarters were not getting pensions.
Last month, Iraq's minister for women resigned, saying the government was not taking the plight of women seriously.
Oxfam said: "Iraqi women are suffering a silent emergency', trapped in a downward spiral of poverty, desperation and personal insecurity despite an overall decrease in violence in the country."
The survey, released to mark International Women's Day, suggested that more than 20% of widows had been victims of domestic violence.
A third of all women surveyed said members of their families had died violently.
Across the country, security improved in 2008, but most women still said that personal safety was their biggest concern.
Almost half said health care provision was worse in 2008 than the two previous years, and almost half of respondents said they were getting poorer.
One widow, Nadia Hussein, told the BBC she found work as a housekeeper after her husband was killed, but the men tried to have sex with her.
Her nephew also beat her regularly.
Women's rights campaigner Hana Adwar said the hardest thing was getting the widows to think that they deserve better.
"The majority feel that this is the will of God, they have to obey the right of their families."