A computer containing the personal details of hundreds of patients at the Royal Bolton Hospital has been stolen.
Thieves took the laptop when they broke into the department for thoracic care, which handles patients with chest and breathing complaints.
The computer contains the information of around 350 patients who receive, or have received, oxygen treatment at home. Details include names, addresses, dates of birth, NHS numbers, GP practices and some details about the patients' oxygen supply.
The hospital has sent letters to those affected and apologised for any concern the theft may cause. Heather Edwards, head of communications at the hospital, said: "While we believe the risk of anybody using the information contained on the computer is extremely small, we thought that it was right for the patients to know what had happened.
"We are very sorry about this and hope it doesn't cause people any undue concern." She said engineers for the company which services the oxygen supplies carried identification cards and that patients should check their ID before letting them in. Mrs Edwards said the information was backed-up and patient health and treatment had not been affected.
Cllr Andy Morgan, chairman of the health scrutiny committee, added: "I will be asking for a full report to be brought to my committee with regards the storage of personal data by both the hospital and the Primary Care Trust, to reassure the public that all is being done to protect their personal information in Bolton."
The theft in November is being investigated by the police. Last October, computer equipment worth around £3,000 and thought to contain important medical information was stolen from the hospital.