The computer was stolen two weeks ago from the Lethbridge Sleep Clinic and contains the information of about 5,000 people.
Officials are now trying to contact these patients to let them know that their names and addresses are on the laptop, but not their personal health records or health care numbers.
Sean Chilton, an AHS spokesman, says the laptop and database were password protected but not encrypted.
The theft has been reported to police, Alberta Health and the Office of the Information and Privacy Commissioner.
In August, the privacy commissioner expressed concern about a laptop that was stolen last year in Edmonton with the health information of 621,000 people, noting that the need to encrypt such information is a "no-brainer."
Chilton called the breach of patient information in Lethbridge inexcusable.
"It's unfortunate this theft of clinic property occurred and we sincerely apologize to any patient impacted by this breach of our information safeguards," he said in a release Friday.
"There is no indication that the information was targeted for fraudulent purposes, and we believe the risk of identity theft is low."