A 19-year-old woman was raped in a caravan at the Reading Festival.
Police arrested a 31-year-old man from London and a 14-year-old boy from Surrey following the attack.
At about 23:30 BST on Thursday, the victim reported being raped in a caravan in the traders' area after meeting a man and a boy in a campsite.
The pair have since been released on bail until 6 October with the condition not to return to the Reading Festival site for the rest of the weekend.
Ch Insp Dave Parker, of Thames Valley Police, said: "We take all allegations of this nature very seriously and we are conducting a full investigation."
Police said there had been 21 crimes at the festival site since Wednesday, including five alleged drugs offences and 13 suspected thefts.