The Vitalite Health Network says the alleged privacy breach took place at the Dr. Georges-L.-Dumont University Hospital Centre in Moncton.
The health board issued a statement Tuesday saying the problem was discovered in February 2013 during a record access audit and a more comprehensive investigation was launched.
It says that investigation has so far found an alleged unauthorized access of records involving 142 patients that took place from Sept. 6, 2010, until Nov. 30, 2012.
The health board says in some cases, information including addresses, phone numbers and dates of birth may have been seen, while in others the employee accessed health record information.
Richard Losier, the chief operating officer for Vitalite's Beausejour zone, says the province's privacy commissioner has been informed and a letter has been sent to affected patients.
Losier says there is no evidence to suggest the information that was accessed was shared or used in any other manner.
The health board says action will be taken if necessary once the investigation is complete.
It did not identify in its statement the physician under investigation.