Authorities do not believe that any health-related information was included.
Officials say they are in the process of informing all affected patients in writing and/or via phone calls.
"We deeply regret that this has occurred, and we understand the concern that patients and their families may feel upon learning that they may have been a victim of this criminal activity," hospital officials said in a statement. "We have, therefore, set up a hotline for patients to call if they have questions, and we will be offering credit monitoring services for affected patients."
NewYork-Presbyterian Hospital is working closely with law enforcement authorities and other government agencies as part of an ongoing investigation.
Officials have also appointed an internal task Force to build upon the hospital's existing systems and to develop a comprehensive program to prevent potential data theft in the future.
Hospital officials say they are taking the matter very seriously. They, and we want to assure our patients and families that we will take all necessary steps to safeguard their personal information.
The hotline number will be provided to the affected patients.
