.The study found 56% of MBA students acknowledged cheating, compared with 54% in engineering, 48% in education, and 45% in law school.

“Business schools have a significant problem that should be addressed,” the study’s lead author and a professor at Rutgers University in New Brunswick, N.J., Donald McCabe, said. Cheating is a problem at all schools, “even if deans at leading schools don’t want to concede it,” he said.

The study offered two main explanations for the cheating: the pressure-cooker atmosphere of business school leaves many students willing to compete by any means available, and corporate scandals have distorted the standards of many business students. The study also said faculties don’t do enough to stop cheating.

The survey, conducted between 2002 and 2004, asked 5,300 students at 54 institutions, including 623 students at 32 graduate business schools, if they ever cheated. The findings will be published this week in the journal Academy of Management Learning & Education.

Officials at top business schools said they didn’t see much cheating. Honor codes that require students to sign a statement on each test saying they had not cheated — and some requiring students to report cheating by others — are a powerful deterrent, as are frequent classroom discussions about ethical behavior, they said.

Student participation in writing honor codes and serving on discipline committees also helps, they said.

At the Wharton School at the University of Pennsylvania, Vice Dean Anjani Jain said cheating is “quite rare.” Each student fills out an evaluation at the end of each class that includes a question about whether cheating has been observed. Philadelphia-based Wharton, with 2,000 MBA students, has between three and seven violations reported to its ethics committee each year, Mr. Jain said in an e-mail.

Cheating is “just not a problem” at Yale University in New Haven, Conn., the chairman of the honor committee at the School of Management, Roger Ibbotson, said in a phone interview last week. “Honesty is a very important part of our school.”

Mr. Ibbotson said Yale’s grading system, which doesn’t use letter grades, discouraged cheating because most students earn the middle grade of “proficient,” the equivalent of B or C, and that discourages cut-throat competition.

“Dartmouth’s honor code fosters an atmosphere of respect for the rules and for fellow students, the dean of Dartmouth College’s Tuck School of Business in Hanover, N.H., Paul Danos, said. “Of course, there are businesses that cheat and people who cheat, but that’s not the way it’s being taught.”

The Tuck School was ranked highest in the nation by recruiters for its students’ academic integrity in a Wall Street Journal/Harris Interactive yearly survey of business schools published last week.

At Stanford University’s Graduate School of Business, the senior associate dean for academic affairs, David Kreps, said cheating isn’t a major issue because a student-run academic committee enforces the honor code and reports to the administration.

The study also suggested that faculty sometimes enable cheating by not creating multiple versions of take-home exams and by sending mixed messages to students. For example, students are encouraged to participate in teams but told they cannot work together on some assignments, the report said.

Earlier studies have found a high incidence of cheating among undergraduate business students. In 1997, Mr. McCabe, a professor of management and global business who is regarded by ethics professors as a leading researcher on cheating and plagiarism, found 84% of undergraduate business students said they cheated at least once, compared with 72% of engineering students and 66% of all students.

In a 1964 study, a Columbia University researcher reported that 66% of business students surveyed at 99 campuses said they cheated at least once.

After the scandals at Enron Corp., WorldCom Inc., and other companies, many business schools added ethics courses or began adding ethics modules to many MBA classes.Wharton created the nation’s only Ph.D. in business ethics three years ago, Mr. Jain said.

Even with the high numbers of cheaters, Mr. McCabe said, “You’re asking kids to be honest about their dishonesty. So that suggests that kids are, if anything, underreporting their cheating activity.”