The study looked at reports for 1,001 consumers issued by Equifax, Experian and TransUnion. The FTC hired researchers to help consumers identify potential errors.
This is the first major study of its kind that looked at all primary groups participating in credit reporting and scoring.
The study also found that after reporting the errors, 20 percent of consumers were able to get the error fixed and about 10 percent of consumers had their credit score changed after corrections were made.
Experts say it's up to consumers to check their credit reports. Anyone who finds an error should file a dispute with the credit bureau and keep all correspondence.
Consumers are entitled to a free copy of their credit report each year.
The Associated Press contributed to this report.