A Black Country hospital trust waited five weeks to inform more than 5,000 patients a laptop with personal details had been stolen, it was revealed yesterday.
The Fujitsu Siemens Lifebook was taken from the outpatients' department at Russells Hall Hospital, in Dudley, between 2.15pm and 4.15pm on January 8.
But patients were only told of the theft when trust bosses sent out letters on Monday, after a risk assessment by Dudley Group of Hospitals NHS Trust, which runs the hospital, and West Midlands Police.
The laptop contains the names, addresses, date of birth, and the anticoagulant clinic attendance, but the trust and police claimed the theft only pose a "low risk" to the 5,123 patients concerned.
Paul Farenden, the trust's chief executive, said it was taken from a clinic which treats people who suffer blood-thinning problems.
A username and password is needed to operate the computer, with a separate username and password required to access the database.
Mr Farenden said there was no evidence to suggest the patient information had been accessed.
"Clearly this is a serious issue. We take precautions to try to protect all the IT equipment in our hospitals from theft but, given that this is a public building with thousands of people accessing it every day, there are inevitably practical difficulties around security," he said.
"Our security team works very hard to ensure the safety of our staff, patients and visitors, but it is very difficult to mitigate against all deliberate acts of theft.
"We would like to apologise for any concern this matter has caused those patients affected, and would like to reassure them that the information on the database is unlikely to be recoverable."