It is "nigh on impossible" to find "visible gay role models" in senior university positions, according to a senior official at campaign group Stonewall.
Charlotte Wheeler-Quinnell, Stonewall's client account manager for workplace programmes, said the lack of role models was "an issue right across the sector".
"Compared with other sectors, where we do have openly gay chief executives...compared with sport, consultancy, law firms, why is it within the universities...we don't have that visibility?" she said.
Ms Wheeler-Quinnell said that with the exception of Dominic Shellard at De Montfort University it was "a bit peculiar" that such role models were not more prominent "given the number of [vice-chancellors]", and suggested there was "almost a perception that if they come out as being gay [this would] distract from their academic career".
"It's going to take someone [to] break the mould. The fact that there isn't anyone [fulfilling this role] at that top level [is a] catch-22," she said.
However, her comments were met with bafflement by one of Stonewall's founders.
Simon Fanshawe, now chair of council at the University of Sussex, said that he could think of two "well-known" gay vice-chancellors who did not hide their sexuality.
"What more should they be doing?" he asked.
He said that it was a "sign of the times" that they were not "gay role models", in Ms Wheeler-Quinnell's words.
"You don't have to be gay as a v-c to show leadership," he said. "You don't have to be gay to say that we should recruit for difference."
Mr Fanshawe said that sexuality was "no bar" to "achieving the highest level" in academia. The lack of women in senior posts was a "much bigger problem", he added.
"[There is] more of an institutional bias against women. I don't detect there's a bias against gay men and women," he said.
Ms Wheeler-Quinnell's comments came as Stonewall released its list of top gay-friendly employers for 2012, in which six universities made the top 100, up from five last year.
The other universities in the 2012 list are the University of Salford (21st), Cardiff University (49th), the University of the West of England (77th) and University College London (83rd).
The ranking is based on self-assessments, interviews and staff surveys on issues such as whether an institution monitors how many of its staff are gay and whether it explicitly includes sexual orientation in policies on equality and bullying.
Sigrid Fisher, head of equality and diversity at Cambridge, said that many committees within the university had a lesbian, gay, bisexual and transgender representative, which was "helpful in terms of advising the university". However, she added that Cambridge does not monitor how many of its staff are gay.