Mahmoud Hussein, the Assiut Brotherhood leader, said the arrests were part of the authorities' "uninterrupted campaign of detentions".
Sunday's roundups brings to almost a 100 the number of Brotherhood members who have been detained since the beginning of March.
Mohammed Osama, a Brotherhood spokesman at its Cairo headquarters, as well as a Cairo police official speaking on condition of anonymity, confirmed Sunday's arrests. Charges have not yet been filed.
A Brotherhood student representative at Assiut University, who refused to give his name fearing police reprisal, said security men stormed students' apartments in three residential areas at dawn and confiscated books and papers.
The Brotherhood representative at the university said there may be demonstrations if the detained students are not freed.
Targeting Brotherhood supporters
On Saturday, police detained 12 suspected members in the al-Sharqiyya and Behira provinces north of Cairo, the Brotherhood's website and police said.
The arrests have focused on provinces where support for the group is strongest and in districts that elected group members to parliament in last year's elections.
While officially outlawed, the Brotherhood put forward 150 candidates who ran as independents in the parliamentary vote late last year.
Candidates from the organisation won 88 seats in the 454-member parliament, increasing its presence more than fivefold in a violence-prone series of votes in which at least 10 people were killed.