Health chiefs in Colchester fired a senior manager who lost confidential records on thousands of patients after his hospital laptop was stolen.
The computer reportedly included 21,000 patients' names, their dates of birth, postcodes and treatments.
The unnamed manager at Colchester Hospital University NHS Foundation Trust in Essex had taken the laptop with him on holiday to Edinburgh. A thief stole the laptop after breaking into the manager's car.
Patients were sent letters about the security blunder, the latest in a series of data losses by public bodies.
The letters said that the computer was password-protected, but the data on it was not encrypted.
The hospital's chief executive, Peter Murphy, announced that the manager was dismissed with immediate effect after a disciplinary hearing on Friday.
He said, "The unanimous decision of the disciplinary panel sends out a clear statement about how seriously the trust takes security and patient confidentiality. I again apologise for the distress the theft of this laptop may have caused."
Murphy also said that the hospital will call in a consultancy to carry out an independent assessment of the trust's procedures on data security.