About 300 employees of the former Iraqi intelligence and security services chanted “Long live the former Iraqi President” in the city of Ba'quba, near Baghdad, on Monday.
The protesters held up pictures of Saddam and some of them carried hand grenades during the march.
They called for their salaries to be paid and for renewed employment.
They also condemned the US occupation of Iraq and the American-appointed governing council.
US forces stationed in the city monitored the protesters, but did not intervene in the demonstration.
The protest followed the killing of a US soldier in a Ba'quba bomb blast earlier in the day.
Several more soldiers were injured in the blast.
The attack was aimed at the US Army's 4th Infantry Division and is thought to be a resistance attack.
Ba'quba has been the scene of several resistance attacks against occupation forces since Saddam Hussein was overthrown in April.