Around 200 people attended an illegal rave in a field near Botolph Claydon over the weekend.
Police were called at about 4am on Sunday and officers from around the Thames Valley were sent to close down the event.
In addition to the ravers, there were about 40 vehicles at the unlicensed event.
A police spokeswoman said: “Reports of this nature are taken extremely seriously by Thames Valley Police, and police are investigating fully.
“Advice for landowners to prevent illegal raves taking place on their land is available on the Thames Valley Police website.”