Manager Brian Talbot has been sacked by Oxford after less than a year in charge of the League Two club, with youth team coach Darren Patterson taking over.
Talbot took over in May 2005
Talbot joined the club in the summer of 2005, but a poor run of results has seen them slip to 22nd in the league.
They have not won a game since they beat Chester on 2 January.
Patterson has agreed a deal until the end of the season and will take charge for the first time against Bristol Rovers on Wednesday.