Human rights groups have urged Iran to lift restrictions on women attending university and enrolling in certain academic fields.
Thirty-six universities across Iran have banned women from 77 different majors, including accounting, counselling, and engineering, for the school year that begins on Saturday, Iran's Mehr news agency reported in August.
There was no official reason given for the move, but Iranian officials have expressed alarm in recent months about the country's declining birth and marriage rates, seen as partially caused by women's rising educational attainment in the last two decades.
In a statement released on Saturday, Human Rights Watch, the New York-based watchdog, urged the Iranian government to immediately reverse the more restrictive policies, and said they were a violation of the international right to education for everyone without discrimination.
"As university students across Iran prepare to start the new academic year, they face serious setbacks, and women students in particular will no longer be able to pursue the education and careers of their choice," Liesl Gerntholtz, women's rights director at Human Rights Watch, said.
Women in Iran make up a majority of college students.
According to Hossein Tavakoli, an official at Iran's National Education Assessment Organisation (NEAO), 60 per cent of those who passed this year's national college entrance exam were women.
Extra curbs have imposed on campuses, particularly a new push to segregate men and women into separate classes to prevent mixing of the sexes frowned upon by Iran's rulers.
Last week the minister of science, research and technology, Kamran Daneshjou, was quoted as aying authorities in the Islamic republic "welcome the establishment of one-gender universities, schools for only men or women."
He said that was the direction "our religion envisions for us."
Daneshjou dismissed Western criticism of Iran's steps, saying: "The angrier Western media gets, the more we realise we are moving in the right direction."
In August, Shirin Ebadi, the Iranian Nobel Peace laureate, argued in a letter to the UN that the closure of certain academic fields to women was part of a push by the Iranian government to stifle "women's presence in the public arena".