The last remaining all-female college at Oxford University has voted to remain single-sex.
St Hilda's has voted against the plans for the second time in a year.
Reformers at St Hilda's failed to gain the two-thirds majority of fellows needed to force a change.
Undergraduates at St Hilda's, founded in 1893, have consistently opposed allowing men to join, saying it would damage their education.
The last ballot on becoming a mixed college, held in March this year, was defeated by just one vote.
Announcing the latest result at the college gates, junior common room president Helen McCabe said: "We are delighted."
The college refused to reveal the breakdown of the vote among the 33 fellows but it was believed to have been very close.
Dr Laura Newby, a lecturer in Chinese at St Hilda's, a known supporter of single-sex status, returned to Britain from a sabbatical in China just to take part.
Julia Blewett, a solicitor who studied classics at St Hilda's, told BBC News Online: "It would be the end of an era if the college became mixed.
"I suspect it will happen within the next 50 or 100 years.
"St Hilda's had a very friendly and relaxed atmosphere. It was a nice college to come home to.
"The social life was outside and when you came back it was less frenetic. Changing its make-up would alter the tone of the college."
At Oxford, just one in five fellows is a woman. Many believe St Hilda's is important in fostering female academic achievement.
Another graduate, Liz Edwards, added: "I'm really glad. Many women applying to Oxford may find prejudice from male dons at interview.
"St Hilda's is a refuge for women. The role models are also encouraging."
Famous old girls
The college principal, Lady English, and the governing body had been criticised recently for holding a vote so soon after the last one and for failing to publicise it properly.
Some dons felt the introduction of men would increase the number of
applications to the college and would improve its financial position.
St Hilda's became the last all-female college in 1992, when Somerville, whose famous old girls include Margaret Thatcher, announced it would admit men.
Oxford still has one remaining all-male constituent college: St Benet's Hall, which takes a small number of students mostly for theological subjects and offers no sciences.