Prince Harry has admitted that he smoked cannabis and drank heavily during last summer.
The drinking and drug taking happened during a period of two months in the summer of 2001, while both Prince Charles and Prince William were away from the family home of Highgrove.
Visited a clinic to help drug users
Since then he has spent a day at a special clinic that helps people who have problems with drugs.
He was taken there by his dad Prince Charles to meet people addicted to very bad drugs to help Harry think more about the dangers.
The News of the World newspaper revealed the story, and a statement from St James Palace didn't deny it.
They confirmed Harry had "experimented with the drug on several occasions" but said he couldn't be described as a "regular" user of cannabis.