The increasing popularity of Jewish "fraternities" is dividing opinion on campuses across the country.
Students at UJS conference earlier this month voted to condemn the groups, accusing them of being "exclusive" and "sexist".
In the past year, many campuses have witnessed the launch of clubs replicating the US Greek system which has often featured in comedy films such as Old School.
The north American system sees brotherhoods and sisterhoods live in designated houses on campuses. Several are Jewish, with their own histories and traditions; Facebook founder Mark Zuckerberg was once a member of the Jewish fraternity Alpha Epsilon Pi, which now has branches in the UK.
Influential in helping alumni build friendships and develop professional contacts, fraternities are also famed for elitism and setting would-be members tough initiation challenges.
The conference motion was proposed by JSoc members from Leeds and Birmingham, where the groups are thriving. It condemned the fraternities' existence, and stated: "At the core of UJS is diversity and equality, and as such our union cannot support organisations which do not share these values."
Delegates also expressed concerns that some fraternities were using facilities that might otherwise be utilised by a university's Jewish society and available to all students.
Aran Clayton, president of the Leeds chapter of Alpha Epsilon Pi, admitted it was a men-only group adopting "special rituals" and exclusive meetings.
But he stressed that planned events, from themed Shabbat dinners to club nights, football matches and charity fundraisers, would be open to all.
He said UJS's stance was due to "a lack of understanding. We are not here to take their people away."
Mr Clayton said fraternities offered a new opportunity for students who tend to stay away from JSoc events to get involved in a Jewish organisation.
UJS president Dan Grabiner said he strongly disagreed with organisations which work with the union having exclusive memberships. He said female students, and those from different Jewish backgrounds, must be welcome.
Mr Grabiner added: "We are in the 21st century and everyone should have equal opportunities."
