A policeman was injured during fighting outside Strattons nightclub in Abingdon.
Security staff at the club struggled to contain groups of youths at the door on Saturday night, and called police.
One officer suffered a leg injury after he fell over during the fracas. He was taken to the John Radcliffe Hospital, Oxford, for treatment and is expected to be off duty for several weeks. No other injuries were reported.
Insp Robin Rickard, of Abingdon police, said it had been a serious public order incident involving groups of drunken and volatile youths.
No arrests were made.
Insp Rickard said: "Statements are being taken from staff at the nightclub but we would also like to hear from anyone who was in the club or outside who can help us."
Last month, at a district council licensing meeting, police criticised rising levels of violent and rowdy behaviour in the town, and opposed the late night opening of a fish and chip shop in The Square.
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