A suicide bomber killed at least 41 people and wounded another 46 outside a university in northeastBaghdadon Sunday.
Iraq's interior ministry said the bomber was wearing a vest packed with explosives.
He detonated the bomb when guards stopped him near the entrance to the business studies school, which is part of Mustansiriyah University, police said.
The same facility in Baghdad'sTalbiyah neighbourhood, a mostly Shia district was hit by a series ofexplosions last month, includingtwin car bombs and a suicide blast thatkilled 70 people.
Most of the victims on Sunday were students at the college, police said. The blast left cement walls pockmarked by shrapnel and twisted parts of the metal gate and turnstile.
The wave of attacks around Baghdad came a day after Prime Minister Nouri al-Maliki lauded the progress of an ongoing U.S.-Iraqi security operation seeking to cripple militant factions and sectarian killings in the capital.
Earlier in the day, two Katyusha rockets hit a Shia enclave in southern Baghdad, killing at least 10, and a bomb near the fortified Green Zone claimed two lives, police said.
The Green Zone houses the U.S. and British embassies and key Iraqi government offices. The blast was about 100 metres from the Iranian Embassy, but authorities did not believe it was targeting the compound.
A separate car bombing in a Shia district in central Baghdad killed at least one person and injured four, police said.
In the northern city of Mosul, U.S. troops killed two gunmen in a raid and captured a suspected local leader of the insurgent group al-Qaeda in Iraq, the military said. Additional details were not immediately available.