Photographer Namir Noor-Eldeen, 22, and driver Saeed Chmagh, 40, were killed in eastern Baghdad during clashes between US forces and militants in the area. It brings the number of Reuters staff killed in Iraq since 2003 to six.
The cause of their deaths was unclear but witnesses spoke of an explosion in the area and Iraqi police said either a US air strike or a mortar attack had occurred.
Since US-led forces invaded Iraq in 2003, 191 journalists and media assistants have been killed, two are still missing and 14 are kidnapped.
Tom Glocer, Reuters chief executive, said: "Once again we are left mourning colleagues who have met an untimely death while doing their job in Iraq.
"Noor-Eldeen and Chmagh's outstanding contribution to reporting on the unfolding events in Iraq has been vital."
David Schlesinger, Reuters editor-in-chief, said that the deaths were a tragic reminder of the risks journalists face in covering the war in Iraq.
He said: "The job our reporters do is a critical one -- telling the world what is happening on the streets of Iraq on a daily basis."
PIC: Victims walk away after a car bomb attack in Baghdad March 15, 2007. REUTERS/Namir Noor-Eldeen (IRAQ)