Personal information relating to 80 children with Asperger's syndrome has been stolen from a Sheffield charity.
A laptop containing names, addresses and medical information was stolen from Asperger's Children and Carers Together (ACCT).
The computer was taken from the home of an employee and reported in December.
The Information Commissioner's Office (ICO) said the incident breached data protection and the charity must ensure "information is encrypted".
The ICO said a hardrive containing the information of 50 young people was also reported as stolen from Wheelbase Motor Project, a charity based in Nottingham.
The hard-drive stolen from the charity's office included information about past criminal and child protection issues of the young people as well their names and addresses.
Sally-Anne Poole from ICO said: "The ICO's guidance is clear - any organisation that stores personal information on a laptop or other portable devices must make sure that the information is encrypted.
"Information about young people's medical conditions or criminal convictions is obviously sensitive and should have been adequately protected."
Both the ACCT and Wheelbase Motor Project said they would ensure personal data was encrypted in future and staff wound undergo appropriate training.