The Brotherhood, which is officially banned, has made a strong showing in the four days of voting held so far, despite arrests of its activists and the blocking of polling stations in Islamist strongholds.
A police source said the arrests were made in areas north of Cairo, including the Nile Delta provinces of al-Sharqia and al-Daqhalia, where voting will take place on 1 and 7 December.
The Brotherhood's website said the authorities had "launched a wide arrest campaign" against delegates of its candidates in the final two days of voting. It said 110 had been detained so far.
The Brotherhood has won 76 of parliament's 444 seats so far - more than five times its strength in the outgoing chamber. The ruling National Democratic Party (NDP) has won at least 195 seats.
The Brotherhood, whose candidates stand as independents, is contesting only about a third of the seats in parliament. It is fielding 49 seats in the final two days of voting for 136 seats.