Abstract: A method of disinfecting an infected electronic file in a file system. At a computer device, a file system is scanned using an anti-virus application to identify the infected electronic file. All or part of an uninfected version of the electronic file is obtained from a backup database of the file system. The backup system includes data from which a plurality of backup copies of at least part of the file system may be obtained. All or part of the infected electronic file is replaced with all or part of the uninfected electronic file. A determination is made as to whether any of the plurality of backup copies include an infected version of the file. If any of the plurality of backup copies include an infected version of the electronic file, the electronic file in the backup database is replaced with all or part of the uninfected version of the electronic file.