A laptop with confidential information about more than 200 children - including their names, addresses, dates of birth and treatment - has been stolen from a Shropshire medical centre.
The thief walked into Madeley Health Centre, Telford, while a speech and language therapist was running a clinic, unplugged her laptop from an adjoining room and walked off with it.
Health chiefs quickly deactivated the laptop to ensure it could not be used to access general NHS data.
But a memory stick plugged into the machine carried details on 238 children, giving their names, addresses, dates of birth and speech and language therapy treatment.
Telford & Wrekin Primary Care Trust has written to all the parents, as well as contacting them by phone, and is carrying out an internal investigation.
Fran Beck, the trust.s director of services for children and young people, apologises for the incident in her letter.
She says the trust takes the security of personal information extremely seriously and has made major security improvements in recent years to protect patient details.
"All our staff have been given strict instructions about all aspects of security - for example, not to leave laptops in cars," she says.
"It is extremely unfortunate this equipment was stolen from an NHS clinic while the therapist was working there."
Telford police spokeswoman Denise Wakefield said the theft of the Flybook laptop happened on February 27 at 4.50pm.
Anyone with information about the theft is asked to call police on 08457 444888.