The data breach comes after Target Corp on Friday said an investigation found a cyber attack compromised the information of at least 70 million customers, in the second-biggest retail cyber attack on record.
Neiman Marcus does not know the number of customers affected by the intrusion, company spokesperson Ginger Reeder said.
Neiman Marcus said its credit card processor alerted the retailer in December about potential unauthorized payment card activities and the U.S. Secret Service is investigating.
A third-party forensics firm confirmed the cyber-security intrusion on January 1, the company said.
Reeder declined to comment if the breach was related to the Target cyber attack.
(Reporting by Kanika Sikka and Natalie Grover in Bangalore and Edwin Chan in San Francisco)