A type of group therapy designed for trauma victims has proved extraordinarily helpful for survivors of sexual violence in Democratic Republic of Congo, enabling women to overcome the shame, nightmares and terrifying flashbacks that had left them unable to work or take care of their families or themselves, researchers report.

An article about the therapy, published Wednesday in The New England Journal of Medicine, is a rare event: a rigorous study of a treatment meant to heal the mental and emotional scars of women in a part of Africa where rape has become a routine weapon of war. Congo, with two decades of civil war, has been called the rape capital of the world by the United Nations. The country has little or no treatment for those with mental health problems.

A team of researchers from Johns Hopkins University, the University of Washington in Seattle and the International Rescue Committee brought a type of treatment called cognitive processing therapy to Congo. They adapted the method to treat women who could not read or write, and taught it to local health workers who had a high school education or less. The workers then conducted group therapy sessions in five languages with survivors of sexual attacks who had severe anxiety, depression and post-traumatic stress disorder. In Swahili, the treatment was called "mind and heart" therapy.

Hundreds of thousands of Congolese females, from toddlers to grandmothers — possibly as many as two million, according to one study— have been raped by rebel fighters or government troops. Notoriously brutal attacks have included gang rapes and penetration with guns, knives and other objects that have torn apart women's reproductive systems and intestines, sometimes beyond repair.

The study included women from 15 rural villages in eastern Congo, an area of rolling green hills and farmland bordered by dense forests where rebels often hide and venture out to conduct raids. Researchers estimate that about 40 percent of the women in the region have been victims of sexual violence.

The therapy technique employed in the study has been used successfully with rape victims and others with post-traumatic stress in the United States. It involves teaching people to think rationally about the troubled thoughts, feelings and beliefs that can linger after an attack.

For instance, women who were raped often blame themselves. They left a window open. They went out alone. They made eye contact with a man who later attacked them. Their clothing somehow invited the assault.

The therapy urges them to question those beliefs. Have women been raped in other circumstances? If so, then how can a woman blame herself?

The program is highly structured, based on a manual for counselors, with topics defined for each therapy session and homework assignments for participants.

Seven villages, with 157 women, were picked at random to receive the group therapy. Eight other villages, with 248 women, were offered "individual support," meaning that the women could ask for personal counseling and referrals for medical, legal and economic problems.

The group therapy consisted of one individual session with a counselor, and 11 weekly two-hour group meetings. The women's symptoms were assessed and graded three times: before the treatment program, when it ended and six months afterward. Sixty-five percent of the women in group therapy completed all three assessments, as did 52 percent of those who got individual support.

The improvement from group therapy was striking, the researchers found. Six months after treatment, only 9 percent of the women who received group therapy still had anxiety, depression or PTSD. By comparison, 42 percent of the women who had individual support still had those problems.

Catherine Poulton, an adviser to the International Rescue Committee, said the group hoped to work with the country's Health Ministry to offer the therapy to more women through national health centers. She said her organization also hoped to provide the treatment in other countries where it was needed. One of the treatment's advantages, she said, is that people without university degrees can learn it.

Janny Jinor, a clinical social worker who helped supervise the study as part of the Johns Hopkins team, observed some sessions and said that a number of women made striking improvements even before the program was complete. One woman, she said, initially showed up unwashed, her hair uncombed and her clothing dirty. She was in her 50s, and had been raped a few years earlier. Her husband rejected her and began to see other women, and her in-laws wanted little to do with her.

But after a few therapy sessions she began grooming herself and wearing clean clothes, and thanked the counselor for helping her to realize that she was an important person. Her family had begun to treat her better, she said.

"She started to shine, and they could see past the woman who was raped, who didn't comb her hair, the one whose fault it was for being raped," Ms. Jinor said.

The women who received group therapy said it had lifted a huge burden, but they had one complaint, Ms. Jinor said: why hadn't they been given this good treatment sooner?

Judith K. Bass, the lead author of the study and an assistant professor in the department of mental health at Johns Hopkins, said: "It's not like it's a miracle cure. It's not like all these women are running into the streets and dancing. But they can go back into the community."

Researchers have also found that sexual violence at home is not uncommon in Congo, in the form of child molesting and marital rape.

"The rate of sexual violence against women in Congo is staggering," Dr. Bass said.

Violence in eastern Congo continued during the study, and one participant was killed.

Debra Kaysen, another author of the study and an associate professor of psychiatry and behavioral sciences at the University of Washington, said, "In two of our villages, during most of the trial, the group leaders, counselor and group members were not able to sleep in their homes at night because it was not safe." She added: "The fact that we got these kinds of results in those kinds of settings certainly bodes well that we can still treat PTSD even in settings that are quite unstable and even in people with very big, real world problems."

Dr. Bass added, "If you can do this in Congo, you can do it anywhere."