About 3,000 Oahu postal employees received letters in the mail this weekend warning them that their personal information may be compromised.
The employees' names, Social Security numbers and other information were on a laptop computer that was stolen in August.
So far, there is no indication the thief was able to access the employees' information, U.S. Postal Service spokesman Duke Gonzales said.
An employee called KITV concerned about why it took so long for the postal service to issue an alert.
"It took so long to notify our employees because it took that long for investigators to determine that one file out of the thousands that were on the laptop contained personal identifying information. As soon as the one file was discovered, the notification process began," Gonzalves said.
The laptop was password protected, Gonzalves said.
Employees are being urged to check their credit card and other financial statements for suspicious activity and to monitor their credit reports.