Eton College has banned Snapchat after concerns that pupils were using it to send sexual pictures.
The elite English public school has blocked access to the instant messaging app from its own wireless network amid fears that boys were using it to send sexts - sexual images, usually of the user.
Messages self-delete after 10 seconds but some pictures can be captured permanently by taking screenshots.
"It is blocked from the Eton wireless internet system," Tony Little, the headmaster, told the Telegraph.
"Boys can still use it via the 3G phone network, but we hope that blocking it on our network will at least make them think twice.
"This is part of our continuing effort to educate boys in the sensible use of technology."
Snapchat recently fell victim to hackers who leaked 4.6 million users' details onto the web.