The great imam of the top Egyptian Islamic institution Al-Azhar said that polygamy can be an "injustice to women and children".
Sheikh Ahmed al-Tayeb, the supreme authority of Sunni Islam, said that the way she is often practiced is due to "a lack of understanding of the Koran."
He made the comment in his weekly television program and on Twitter.
After an exciting debate, al-Azhar made it clear that the cleric did not demand a ban on polygamy.
He repeated that monogamy was the rule and polygamy the exception.
"Those who say marriage must be polygamous are all wrong," he said. The Koran stated that a Muslim who has multiple wives "must follow the conditions of fairness – and if there is no fairness, it is forbidden to have multiple wives".
Sheikh al-Tayeb also advocated a more comprehensive overhaul of the way women's issues are treated.
"Women are half of society. If we do not care about them, it's like walking with one foot," he said on Twitter.
The Egyptian Women's Council responded positively to his comments.
"The Muslim religion honors women – it brought with it justice and many rights that did not exist before," said Maya Morsi, president of the council.