ATLANTA - It's a startling number: One woman in four surveyed by the government says she was violently attacked by a husband or boyfriend.

Experts in domestic violence don't find it very surprising, although some aspects of the survey may have led to higher numbers than are sometimes reported. Even so, a government official who oversaw the research called the results "astounding."

"It's the first time we've had this kind of estimate" on the prevalence of intimate-partner violence, said Linda Degutis of the Centers for Disease Control and Prevention.

The survey, released by the CDC on Wednesday, marks the start of an annual project to look at how many women say they have been abused.

One expert called the new report's estimate on rape and attempted rape "extremely high," with one woman in five saying she was a victim. About half those cases involved intimate partners. No documentation was sought to verify the women's reports, which were made anonymously.

Advocates say the new rape numbers are plausible.

"It's a major problem that often is underestimated and overlooked," said Linda James, director of health for Futures Without Violence, a San Francisco organization that advocates against domestic abuse.

The CDC report is based on a randomized telephone survey of about 9,000 women and 7,400 men. Among the findings:

As many as 29 million women say they have suffered severe, frightening physical violence from a boyfriend, spouse, or other intimate partner.

That number grows to 36 million if slapping, pushing, and shoving are counted.

Almost half the women who reported rape or attempted rape said it happened when they were 17 or younger.

As many as one woman in three has experienced rape, physical violence, or stalking by an intimate partner, compared with about 1 in 10 men.

Both men and women who had been menaced or attacked in those ways reported more health problems. Female victims, in particular, had significantly higher rates of irritable-bowel syndrome, asthma, frequent headaches, and difficulty sleeping.

Certain states seemed to have higher reports of sexual violence than others. Alaska, Oregon, and Nevada were among the highest in rapes and attempted rapes of women. Virginia and Tennessee were among the lowest.

Several of the CDC numbers are higher than those of other sources. For example, the CDC study suggests that 1.3 million women have suffered rape, attempted rape, or had sex forced on them in the previous year. That is more than seven times greater than what was reported by a Justice Department household survey conducted last year.

The CDC rape numbers seem "extremely high," but there may be several reasons for the differences, including how the surveys were done, who chose to participate in the surveys, and how rape and other types of assault were defined or interpreted, said Shannan Catalano, a statistician with the Bureau of Justice Statistics.