Around 600,000 current and former employees could be affected by the privacy breach, according to reports, although Time Warner has confirmed that the tapes did not include the personal data of its customers.
The media and entertainment giant is notifying those individuals whose information may have been on the missing tapes, and is advising them on how best to protect themselves in the event that the data has been stolen.
"We take the security of our employees' personal information extremely seriously and we deeply regret that this incident occurred," said Larry Cockell, Time Warner's Senior Vice President and Chief Security Officer.
"While we have no evidence to suggest the information on the tapes has been accessed or misused, we are providing current and former employees with resources to monitor their credit reports while our investigation continues. We are working closely and aggressively with law enforcement and the outside data storage firm to get to the bottom of this matter," he added.
The loss is the latest in a string of high profile privacy breaches to hit the headlines recently, including the disappearance of backup tapes containing the credit card information of 1.2 million federal workers by Bank of America, the theft of around 310,000 customers' personal information at a subsidiary of data broker LexisNexis, and the reported loss of transaction data belonging to around 180,000 customers of fashion house Polo Ralph Lauren.