Student party organisers have caused a major row by asking guests to come in fancy dress - and be accompanied by "a fit Jew".
Guests were told to find female students as dates and dress up, complete with money-bags and wear fake peyot (sidelocks).
The event was cancelled following complaints from Jewish students and Oxford University's student union is now carrying out an investigation.
The Union of Jewish Students said it was appalled by the use of "antisemitic stereotypes" that had left a "stain on the reputation" of the university.
Members of the under 21 rugby team were due to begin their night out at a curry house before moving to a nightclub.
Team captain Phil Boon was reported in the student newspaper as saying he "didn't see what the problem was" and that it would have been "an awesome social".
Sports clubs at the university traditionally take part in "crew date" social events. Players are allowed to choose a fancy dress theme.
An Oxford University spokeswoman said: "The University condemns unreservedly racial stereotyping.
"The University reaffirms its commitment to promoting good race relations and condemns any form of religious discrimination."
A UJS spokesman said: "The actions of a few individuals have caused real offence. UJS is appalled that in 2008 old myths and antisemitic stereotypes are still appearing among supposedly educated students.
"It is clear that this is only an ignorant minority. Incidents like this remain a stain on the reputation of universities."
National Union of Students president Wes Streeting said his organisation stood "side-by-side" with UJS, adding: "It brings the wider Oxford University community into disrepute."