Bitter emotions in al-Aadhamiya left few doubts that whoever leads Iraq after December elections has a long way to go to win over the trust of the Sunni community.
Sunnis interviewed in other parts of Baghdad were divided over the constitution, some voting yes and others no.
But there were no mixed signals in the capital's Sunni heartland fiercely opposed to the charter drafted by Shia and Kurdish leaders.
The mood in the al-Aadhamiya district of the capital on Saturday contrasted sharply with other areas, even nearby Sunni districts.
"Of course I am voting no," said Muhammad Hasan. "This document neglects the Sunnis and it just helps the Shia. We want a united Iraq , not one that is carved up into federal states."
The constitution has deepened frustrations among many Sunnis who worry that it will give Shia and Kurds power and oil resources in regions where they dominate and leave Sunnis disadvantaged.
Many Sunnis also say Iraq's Shia leaders are heavily influenced by Shia Iran.
Although it was impossible to tell if any Sunni guerrillas went to al-Aadhamiya ballot boxes to reject the charter, teenagers around the voting station had the same stern faces as the young men who fill the ranks of the uprising.
Many voters cast a no vote to the
"No, no, no," chanted one group of young men as they entered the polling station.
"This constitution was made by the Americans and Israelis and Iran and their friends in the Iraqi government," said a teenager as his friends nodded in agreement.
A man and his wife came out smiling and saying they had voted yes. But they turned out to be Shia living in al-Aadhamiya, a sprawling district with mostly two-storey houses.
Few policemen were in sight as voters walked along narrow roads to vote in the Safina school, unlike other polling stations heavily guarded by Iraqi and US forces backed by Bradley fighting vehicles.
"This constitution was made by the Americans and Israelis and Iran and their friends in the Iraqi government"
Unidentified armed groups in al-Aadhamiya have warned that Iraqis who work with Americans or the Iraqi security forces will be killed. Some people have been shot or beheaded and left on the side of the road with a sign with the word "spy" left on their chests.
Some voters said they knew nothing about the constitution, but that did not stop them from rejecting it.
"I don't know anything about it. Nobody told us. But I said no. After all, it was drawn up by the Americans," said Ahmad Abu Zahra.
As they left the polling station, two young men tried to outdo one another on how they rejected the charter.
"I said no and no, said one. "The government asked us to say yes but I said no twice," said his friend.