At least one person was killed in the Shiite Muslim holy city of Karbala late on Monday, the Iraqi Human Rights Commission said. An AFP correspondent reported live rounds were fired near the provincial council headquarters.
The death brought to 240 the overall toll since anti-government rallies erupted in Baghdad and southern cities on October 1. More than 8,000 people have been wounded.
In the capital's iconic Tahrir (Liberation) Square, hundreds of young protesters woke up after a fifth night in tents, abandoned buildings or camped out on the pavement.
They had defied an order by the military to clear the streets between midnight and 6:00 am (0300 GMT), heading defiantly to the square by car or on foot.
"Their curfew changed nothing," said 30-year-old protester Duaa, adding that she had driven around Baghdad for several hours before returning to Tahrir during the night.
"Did the government think we would stay at home? No way," she told AFP.
Protesters have been demanding an overhaul of the political system which they say has failed to take action against chronic unemployment or widespread corruption.
They have been joined by thousands of students and schoolchildren in recent days.
Trade unions representing teachers, lawyers and dentists have all declared strikes lasting several days.